The Index of Countries’ Support for UN-based Multilateralism: Construction, Verification,  and Correlates^*

In 2024, multilateralism faces strong headwinds. It is often considered fragmented or even in crisis (Jones and Malcorra 2020; Gowan 2022; Puglierin 2023). Recently, the international community failed to prevent and respond effectively to the COVID-19 pandemic (Sachs et al. 2022). Global diplomacy, including via the United Nations (UN), seems unable to resolve many of the ongoing military conflicts including in South Sudan, Yemen, and, recently, in Ukraine or Gaza. Six of the nine planetary boundaries have been breached and, collectively, humanity is eroding the biological and physical resilience of Earth's physical systems and is failing to safeguard the Global Commons through more effective global governance mechanisms (Biermann et al. 2022; Richardson et al. 2023; Ishii et al. 2024). The international financial architecture is failing to channel global savings to investments at the needed pace and scale to achieve the Sustainable Development Goals (SDGs), and the Paris Climate Agreement, especially in the poorest nations (Sachs, Schmidt-Traub, and Lafortune 2020; Sachs et al. 2023; Sachs et al. 2023). Some scholars, national leaders, and international practitioners have called for major reforms of the UN Security Council (Wouters and Ruys 2005; Dabhade 2022), Bretton Woods Institutions (Gallagher et al. 2023; Espinosa 2023), and some recently proposed new global governance frameworks and paradigms to protect planetary commons and strengthen the UN system (Rockström et al. 2024; d’Orville 2023).

Considering the global nature of today's challenges—including climate change—global cooperation and UN-based multilateralism must underpin any effort to move toward the triple-bottom-line of sustainable development (social, economic, and environmental) and meet the needs of future generations (Brundtland 1987; Jeurissen and Elkington 2000; Sachs et al. 2019). Keohane (1990) defines multilateralism as “the practice of coordinating national policies in groups of three or more states, through ad hoc arrangements or using institutions.” The international community relies on “rules and norms to manage flows of people, goods, and investment, and to regulate the use of force among countries” (Woods 2023).

Traditionally, leading realists’ scholars tend to discuss the false promises of international institutions (Mearsheimer 1994). In contrast, leading liberal scholars, including Keohane (1989) and Ruggie (1992), argue that, under certain conditions, multilateralism and international norms and institutions can facilitate global cooperation by enshrining commitments to diffuse reciprocity and peaceful dispute settlement.

This paper focuses on the specific form of multilateralism at the center of international law—UN-based multilateralism—and aims to evaluate, in a structured and quantitative way, the efforts made by Nation-States to promote or undermine UN-based multilateralism based on the principles set in the UN Charter in 1945. For the first time, this paper presents a new Index of countries’ support for UN-based multilateralism (UN-Mi) using six headline indicators—(i) UN treaty ratification, (ii) votes aligned with the majority at the UN General Assembly, (iii) membership in UN organizations, (iv) participation in conflicts and militarization, (v) use of unilateral coercive measures against other Nation-States, and (vi) contribution to the UN budget and international solidarity—and discusses its implications in the era of long-term global commitments for sustainable development. More specifically it aims to answer the following three questions:

• How can countries’ support for UN-based multilateralism be measured?

• Which countries and regions are most and least committed to UN-based multilateralism?

• How has the support of major economies for UN-based multilateralism evolved over time?

While other country-level studies have focused on related concepts, such as the size of diplomatic networks, people's confidence in global cooperation and the UN system, or SDG implementation, it is, to our knowledge, the first attempt to quantify in a structured and quantitative way countries’ support for UN-based multilateralism. It aims to provide new contributions to the field of International Political Economy—“the study of the reciprocal relationship between politics and economics in the global system . . . , which builds on some of the insights and the familial frameworks of the various International Relations theories by linking political actors across states to international economic relations” (Walzenbach 2022)—building inter alia on public economics and international relations theories and statistical methods. A sound, structured and evidence-based diagnosis of countries’ support for UN-based multilateralism is important to make governments accountable for adhering to the principles of the UN Charter and inform global debates on how to strengthen and reform the UN system to address the challenges of the 21st century.

Overall, our findings suggest that most of the world population lives in a country where support for UN-based multilateralism is high and has increased compared with the early years of the UN. However, there are significant differences across countries and indicators, with some of the greatest powers showcasing low and declining support for UN-based multilateralism. The poor performance of the United States and some of its allies suggests that the concepts of “rules-based international order” (RBIO) and “UN-based multilateralism” are truly distinct, and arguably, even opposite, frameworks. Our statistical analysis confirms that the UN-Mi captures something different than other existing constructs that aim to capture, for instance, the size of diplomatic networks or people's confidence in the UN. We hope our findings can provide useful evidence and possibly impetus to strengthen the UN system and address the shared global challenges of our time.

Our focus on UN-based multilateralism is distinct from other conceptual alternatives, such as the RBIO. Concepts like RBIO, used notably in the National Security Strategy of the United States (White House 2022), and primarily by other Western countries, have never been explicitly defined (Talmon 2019; Vylegzhanin et al. 2021). Some argue that RBIO might prioritize the interests and values of specific nations or groups of nations over international law and treaties and be at the expense of the global public good (Dugard 2023; Congyan 2023). Many countries promote the “international law-based international order” based on the UN Charter, international law, and UN institutions, and, crucially, on the Doctrine of Non-Intervention in the internal affairs of other nations (Congyan 2023).

There is a large body of literature that aims to measure the effectiveness of international law, UN institutions, and global cooperation. Both the Index of Multilateralism (International Peace Institute et Institute for Economics and Peace 2022) and the Global Solidarity Report (Global Nation 2023) usefully explore the state of multilateralism focusing on the world as one single observation but not providing overall results country-by-country. The OECD pioneered groundbreaking work to evaluate the effectiveness of international organizations (OECD 2016, 2019, 2021) and various studies have analyzed the population's support for global cooperation and the UN, using household survey data (Torgler 2008; Trithart and Case 2023; Garton Ash, Krastev, and Leonard 2023).

Some initiatives track specific aspects of Nation-States’ multilateral behavior. The SDG Index measures countries’ progress towards achieving the UN SDGs using primarily outcome statistics (Schmidt-Traub et al. 2017; Lafortune et al. 2018; Sachs et al. 2023). To track SDG17 (Partnerships for the Goals), the authors of the SDG Index use indicators of domestic resource mobilization, international tax cooperation (SDG 17.1), or statistical performance (SDG 17.18). Bibliometric analysis has also been used recently to evaluate the impact of multiple crises on the achievement of global goals (Leal Filho et al. 2023). Other initiatives measure the size of diplomatic representation (Lowy Institute 2021), efforts to promote peace and demilitarization (IEP 2022), trade openness (UNCTAD 2023), or countries’ positive and negative spillovers (Anholt 2021; SDSN, Yale Center for Environmental Law and Policy, and Center for Global Commons at the University of Tokyo 2021; Lafortune et al. 2021; Ishii et al. 2024). For decades, scholars have analyzed voting patterns at the United Nations General Assembly mainly to identify coalitions, alliances, and blocs on certain international political issues (Ball 1951; Lijphart 1963; Dreher, Nunnenkamp, and Thiele 2006; Voeten 2012; Bailey, Strezhnev, and Voeten 2017). Scholars have also looked at the status of treaty ratification across country groups—for instance, recently across Asian sub-regions (Le, Ho, and Inoguchi 2023; Le and Ho 2024).

Good data and clear metrics are critical for establishing a fair diagnosis of countries’ intention to engage with the UN, understanding the drivers of countries’ support for UN-based multilateralism, and strengthening the functioning of the UN. Yet, none of these initiatives track in a universal, structured, and quantitative way countries’ support for UN-based multilateralism. Building on Keohane's definition of multilateralism, we define UN-based multilateralism as the practice of coordinating national policies following the values and procedures of the United Nations epitomized by Article 1 of the UN Charter. Our goal is to capture intentionality to engage with UN-based multilateralism. Other initiatives track in various ways various aspects of the implementation of UN treaties, including various aspects of the UN Declaration of Human Rights (1948), such as health and education outcomes (WHO 2024; UNESCO 2023), or freedom of speech (Reporters Without Borders 2024), among others.

There is no single indicator that can capture comprehensively countries’ support for UN-based multilateralism. Although they have well-known weaknesses, composite indices that build on a combination of indicators can help “synthesize complex information into a single number and may be more effective in stimulating public debates than a large number of individual scores that could result in cherry-picking” (Schmidt-Traub et al. 2017). As emphasized by the UN Statistics Division (UNSD), “A long list of indicators is neither communicable nor effective in galvanizing public support” (2015). As presented in the Appendix, we followed the steps described in the Joint Research Committee and OECD handbook to design a sound composite index (OECD and JRC 2008).

Our conceptual framework to measure countries’ support for UN-based multilateralism is Article 1 of the UN Charter and its four paragraphs. These define the core purposes of the UN. As such, our conceptual framework is different and narrower than other initiatives that aim for instance to measure global solidarity at large (Global Nation 2023), or the broader concept of a “Good Country” (Anholt 2021). Building on UNSD (2015), we identified clear criteria for the indicator selection (relevance, country coverage, time coverage, methodological soundness, and limited in number). Our objective is to capture overall engagement with UN-based multilateralism, rather than sectoral policy engagement—for instance in international trade, fiscal, migration, environment, health, or education policy.

Overall, we found that most countries demonstrated relatively high support for UN-based multilateralism. The average UN-Mi across 193 UN member states was equal to 65 and the median was 70. We estimate that 90 percent of the world population lives in a country with an UN-Mi score above 50—this means more than half of the way toward perfect support for UN-based multilateralism. As an example, out of 193 UN member states, 90 percent ratified two-thirds or more of the major UN treaties, 66 percent voted with the international majority at UNGA two-thirds of the time or more, more than half (55 percent) were members of the 24 organizations and entities considered, 80 percent had limited or no participation in conflicts and militarization (score below 2 out of 4 on the adjusted Global Peace Index), around 70 percent made no use or very limited use of UCMs (i.e., have less than 5 UCMs currently in place) and the vast majority of countries were not subject to the provisions of Article 19 related to significant arrears in the payment of dues to the UN.

On average, Latin America and the Caribbean, East Asia and Pacific, and Sub-Saharan Africa tended to be particularly supportive of UN-based multilateralism, with average scores of 68 and above. Compared with other regions, the score of Latin America and the Caribbean was rather homogeneous, with a minimum value above 50 and with standard deviation below 10. Looking at other country groupings and coalitions, ASEAN, Small Island Developing States (SIDS), African Union, G77, and the EU tended to perform above the world average. The BRICS (Brazil, the Russian Federation, India, China and South Africa) and BRICS countries (including all the BRICS and countries invited to join the BRICS in 2023, namely Argentina, Egypt, Ethiopia, Islamic Republic of Iran, Saudi Arabia, and the United Arab Emirates) were on par with the world average. Among ASEAN member states, Malaysia, the Philippines, and Vietnam performed particularly well, with overall scores exceeding 80, whereas Myanmar was the worst ASEAN performer, with a score of 51. By contrast, North America, NATO, OECD, P5 (The UN Security Council's five permanent members: the United States, China, France, the Russian Federation, and the United Kingdom), Nuclear Powers (China, India, United Kingdom, Pakistan, France, Russian Federation, Democratic People's Republic of Korea, Israel, and the United States), and G20 tended to perform below the world average UN-Mi. This was partly driven by the low scores of the United States and the Russian Federation.

We explored correlations between the UN-Mi and other related variables of engagement with multilateral processes and country characteristics. The summary table is included in the SI. This broad empirical evidence can, in part, be taken as evidence of construct validity (i.e., the UN-Mi consistently correlates with measures that should influence or should be influenced by countries’ support of UN-based multilateralism according to theory; OECD 2017).

Overall, we found a statistically significant correlation between the UN-Mi and countries’ engagement with the current global set of goals for sustainable development—the SDGs—using the score of “Government effort and commitment for the SDGs,” which captures the use of the SDGs in public policies (speeches, budget, indicators) and countries’ efforts to report regularly their action plan and progress to the rest of the international community via the so-called UN Voluntary National Reviews (Sachs et al. 2023; Lafortune, Woelm, and Valentiny 2022). In 2023, five countries never engaged with the Voluntary National Review process—Haiti, South Sudan, Myanmar, the United States, and Yemen—and these countries are also among the bottom 25 percent performers in the UN-Mi. A high UN-Mi also tended to be associated with higher levels of structural vulnerability (including vulnerability to extreme weather events and climate change) and lower negative impacts on the Global Commons. A higher UN-Mi was also associated with higher implementation of the Rule of Law when HICs were excluded from the sample, yet the Rule of Law did not seem to be a differentiating factor among HICs. Antigua and Barbuda, Barbados, Chile, and Uruguay (which were all HICs) performed very well on the UN-Mi, although, according to the 2023 Rule of Law Index, they were among the bottom half performers in implementing the Rule of Law among HICs (World Justice Project 2023).

Our analysis also confirmed that the UN-Mi captured something different from the size of diplomatic networks, existing measures of SDG17 (Partnerships for the Goals), and the Good Country Index. The size of diplomatic networks, as measured by the Global Diplomacy Index from the Lowy Institute (number of embassies, consulates, permanent missions, and other forms of representation), is almost collinear with countries’ economic size, as measured by nominal GDP (logged). The Good Country Index has a broader approach to measuring countries’ positive global contributions (including the number of international students, registered patents, and birth rate), which in many cases correlated well with per capita GDP. Interestingly, the UN-Mi did not correlate with existing measures of the population's trust in the UN (or related concepts) and the level of engagement of cities and regions with the SDGs, as measured by the number of voluntary local reviews submitted.

The SI provides additional information related to the sensitivity of the UN-Mi to a different weighting scheme and aggregation method. This analysis confirmed that the UN-Mi is fairly robust, especially at the top and bottom of the distribution.

Finally, we present an assessment over time of countries’ support of UN-based multilateralism focusing on 58 countries that joined the UN between 1945 and 1950. Together, these 58 countries represent 72 percent of the current world population. Due to data gaps and limitations, we made some adjustments to the indicators that are described in the Appendix section. We could not track over time the payments of contributions to the UN and we replaced the Global Peace Index (available only since 2008) with military expenditure as a percentage of GDP. Results are presented by decade to focus on structural trends rather than year-on-year changes.

Overall, we found that most countries, on average, tended to be more committed to UN-based multilateralism over the period 2010–23, than in the decade 1960–69. We used the 1960s as our main benchmark because our goal was to analyze long-term trends and because by the 1960s the countries in our sample had been UN member states for at least ten years. Compared with the 1960s, we found that the majority of countries tended to ratify more UN treaties (as a share of the cumulative total number of instruments possible to ratify by decade), reduce their military expenditure as a share of the economy, and vote more often with the rest of the international community at UNGA (while the size of the majority tends to remain stable on average across decades at around 70 percent), and to participate more in UN organizations and entities. However, the use of UCMs was more widespread in the 2010s than in the 1960s, driven largely by the growing use of UCMs since the 1990s.

We would like to emphasize four major findings from our study. Firstly, it is possible to measure universally and in a statistically valid and robust way countries’ support for UN-based multilateralism. By doing so, we reject the hypothesis that countries’ public support of the broader concept of global “Rules-Based Order” is always conducive to high support for UN-based multilateralism under the UN Charter. Secondly, we find that most people live in countries where support for UN-based multilateralism is high and increasing when compared with the early years of the UN. At the same time, some of the largest economies demonstrate relatively lower support for UN-based multilateralism. Thirdly, we found positive correlations between countries’ UN-Mi and countries’ engagement with the SDGs and other global objectives such as limiting negative impacts on the Global Commons. Fourthly, focusing on structural long-term trends, most of the world population lives in a country that is more supportive of UN-based multilateralism now (average 2010–23 period) than in the 1960s, although there are significant variations across countries and indicators. Short-term trends on military expenditure and adoption of UCMs (and possibly other measures) may indicate, however, a decline in support for UN-based multilateralism over the past two years. The COVID-19 pandemic and recent military conflicts—including the intensification of military tensions in Ukraine since 2022—may have impacted country results on the variables related to participation in conflicts and militarization and votes aligned with the majority at UNGA. These global crises and failure to respond effectively might also be the consequence of limited support for UN-based multilateralism by some UN member states.

It is notable, or one might say fundamental, regarding the current state of international relations, that the United States ranks last in the UN-Mi with poor or below-average results across all six dimensions. The United States is the lead promoter of the RBIO yet is last in terms of support for UN-based multilateralism. This suggests that the RBIO and “UN-based multilateralism” are truly distinct, and arguably, even opposite, frameworks. The rules-based order is the set of behaviors or rules favored by the United States and its allies. The UN-led order is the set of rules established by international law and UN institutions. Regarding the sub-components of the UN-Mi, the United States ratified only around 60 percent of major UN treaties (and one-third of the nine UN Human Rights’ Treaties), voted with the international majority at UNGA less than 25 percent of the time over the past five years (2018–22) (and on average over a longer period [1950–2022]), is not a member of UNIDO and the UN World Tourism Organization, and left on several occasions UN organizations and agencies including UNESCO; it actively participates in conflicts and militarization, it uses UCMs more than any other country in the world, in particular, since the 1990s, and committed only around 0.18 percent of its GNI to ODA between 2018 and 2022—far from the international target of 0.7 percent. In the context of Agenda 2030 and the SDGs, as of April 2024, the United States is one of the five UN member states in the world that never took part in the UN Voluntary National Review process (Sachs et al. 2023).

One interesting finding is that the UN-Mi does not seem to correlate with any measures of people's confidence in the UN and with the engagement of subnational entities (cities and regions) with multilateral processes. This suggests that the UN-Mi measures primarily the support of national governments or the “elite,” which may not reflect the views of the people and civil society regarding the UN and global cooperation. As one example, while the United States performs last in the UN-Mi, a YouGov survey conducted in August 2020 shows that 30 percent of people in the United States considered that the “country should be doing less to act on its own and more to coordinate its response with other countries in tackling the pandemic,” which is among the highest percentage among the 24 countries covered (Nolsoe 2021). Similarly, despite its relatively poor performance on the UN-Mi, a recent study showed that more than half of the population in the Russian Federation considers that a good leader is one who “seeks the best for its country through international cooperation” as opposed to only “standing up for its own independence” (Garton Ash, Krastev, and Leonard 2023). Some countries with low UN-Mi scores do demonstrate high support for multilateral processes at the subnational, via the preparation of SDG Voluntary Local Reviews (VLRs) for instance. The United States is one of the 38 countries where subnational entities have submitted VLRs, nine in total, with New York City being the first city in the world to prepare and submit a VLR in 2018 (UNDESA 2024).

The UN-Mi has a clear scope and purpose: to measure efforts to promote UN-based multilateralism covering all 193 UN member states. As such, the UN-Mi may not capture countries’ diplomatic efforts and engagement with other forms of bilateral and regional partnerships. In the Asian context, other scholars have looked at the benefits and challenges related or instance to regional trade agreements and digital currency initiatives (Lee and Park 2005; Chia 2015; Eichengreen and Viswanath-Natraj 2022). The UN-Mi measures the ratification of UN treaties but not their effective implementation in practice. Similarly, it measures membership status in organizations but not the active and constructive contributions of countries within these organizations.

The UN-Mi uses indicators with universal or near-universal coverage. Over time, we hope to be able to refine our indicator selection and define sound methodologies to capture not only “extreme” arrears of payments under Article 19 as listed by the UN but also recurring delays in payment of contributions as well as non-military interference in domestic affairs of other countries (including via cyberwarfare).

Yet, available evidence suggests that the inclusion of such metrics would most likely reinforce our findings rather than contradict them. Over the last 30 years, according to UN records and academic research, the United States and other countries at the bottom of UN-Mi ranking accumulated large arrears to the UN (United Nations 2024; Bond 2003). According to Levin (2019), 117 partisan electoral interventions were made by the United States and the USSR/Russian Federation between 1 January 1946 and 31 December 2000 (69 percent by the United States and 31 percent by the USSR/Russian Federation)—two countries that perform poorly on the UN-Mi. O'Rourke (2018) finds that between 1947 and 1989, the United States tried to change other nations’ governments 72 times, with 66 covert operations and six overt ones. Due to limitations in data completeness and attribution, cyberwarfare is currently excluded from the UN-Mi despite its potential to impact friendly relationships among nations as called for by the UN Charter. As emphasized by Mezzour et al. (2014), “cyber criminals behind attacks in Central America are probably from other regions, but choose this region for conducting cybercrime because of attractive conditions there.” The Cyber Threat Intelligence team ranks China and the United States as the place of origin of more than one-third of global cyberattacks in 2021, yet it is difficult to distinguish between state-sponsored versus criminal operations (DavidPur 2022). The Council on Foreign Relations tracks suspected state-sponsored cyberattacks but recognizes that the current methodology tends to over-report “incidents or threat actors affecting countries where English is widely spoken” (Council on Foreign Relations 2023).

Overall, this paper argues that it is possible to measure validly and robustly countries’ support for UN-based multilateralism. Nations States hold the primary responsibility for making UN-based multilateralism work and they should therefore be held accountable for implementing the principles of the UN epitomized in the UN Charter of 1945. Our main conclusion is that most of the world population lives in a country where support for UN-based multilateralism is high and has increased compared with the early years of the UN in the 1950s and 1960s, although there are significant differences across countries and indicators. Our study also suggests that the concept of “UN-based multilateralism” is distinct from other related concepts, including the concept of “Rules-Based International Order” used notably by the United States and its allies. Further research is needed to refine the indicator set notably with universal and sound measures of cyberwarfare and non-military interference on other countries’ affairs, but also to understand the drivers of countries’ support for UN-based multilateralism over different periods, which is beyond the scope of this study.

Eighty years after the creation of the UN, this analysis should provide momentum to strengthen the UN system to address the shared global challenges of our time—including implementing the SDGs and the Paris Climate Agreement. From a practical perspective, new global mechanisms and perhaps institutions must be considered to address global challenges in a context of low and declining support for UN-based multilateralism among some of the greatest powers. As such, the introduction of global taxation, for example, on CO2 emissions, air travel and financial transactions may help to mobilize the financial resources needed to help the UN fulfill its global missions and needed global public goods. Our findings might also support the proposal made by other practitioners and scholars to create a “UN Parliament” to establish the representation of We the Peoples in the UN and strengthen oversight of UN norms and procedures, including the budget (Sachs, Lafortune, and Fuller 2024; CUNPA 2024). Yet, considering that to this day Nations States’ support is needed for any major reform of the UN system, we underscore the importance of sound, transparent, universal, quantitative and regular assessments of countries’ support for UN-based multilateralism to make UN member states accountable to their peers and population for their adherence to the UN Charter.

Nation-States continue to hold the primary responsibility for promoting effective UN-based multilateralism. The UN is based on the principle of sovereign equality of all its members. Each country has one vote at the UN General Assembly. Nation-States are responsible for signing, ratifying, and implementing international treaties and conventions. The sixth edition of “The UN in the 21st Century” report recalls that “the UN is the creation of its member states; it is they who decide what it is that they will allow this organization to do and what resources—financial and otherwise—they will provide. Thus the UN is very much subject to the winds of world politics and the whims of member governments” (Mingst, Karns, and Lyon 2022). Nation-States should, therefore, be accountable for promoting UN-based multilateralism and making global cooperation fit for 21st-century challenges. Yet, despite the vast literature on multilateralism and global cooperation, there is to our knowledge no comprehensive, structured, and quantitative assessment of countries’ support for UN-based multilateralism.

The UN Charter adopted in 1945 guides the purposes and principles of the UN. Based on Article 1 of the UN Charter, the UN is an international organization created to “maintain international peace” (Article 1.1), “develop friendly relationships among nations” (Article 1.2), “achieve international co-operation in solving international problems of an economic, social, cultural, or humanitarian character” (Article 1.3), and “be a Center for harmonizing the actions of nations in the attainment of these common ends” (Article 1.4). The UN's membership has grown from the original 51 Member States in 1945 to the current 193 Member States. We do not discuss bilateral and regional partnerships and coalitions (such as countries’ involvement in ASEAN, MERCOSUR, European Union, etc.), the role of regional institutions and economic fora (such as regional development banks but also the G77, G20, G7, BRICs, and OECD multilateral formats), but focus only on countries’ commitment to global cooperation via the UN system.

Our objective was to measure countries’ support for UN-based multilateralism. Our conceptual framework is the UN Charter (1945) and the four paragraphs under Article 1. We used five main criteria for selecting the indicators: (1) relevance, (2) country coverage, (3) time coverage, (4) methodological soundness, and (5) limited in number. In total, 17 indicators were considered for inclusion. Six indicators were retained. The SI provides additional tables related to the criteria for the indicator selection the indicators considered for inclusion and the reasons for their non-inclusion.

A pilot version of the UN-Mi covering 74 countries was published in the Sustainable Development Report 2023 (Sachs et al. 2023) and the indicator selection and detailed methodology were submitted for public consultation between November 2023 and February 2024 (Sachs, Lafortune and Drumm 2023). Preliminary results were discussed and presented at the Workshop on the Summit of the Future in March 2024 organized by the UN Sustainable Development Solutions Network and the Pontifical Academy of Social Sciences.

We used six headline indicators to compile the UN-Mi. The indicators related to treaty ratification, UNGA votes, membership in UN organizations, and financial contribution to the UN were compiled using the UN Web site and database either via desk research or Python Web scraping. The other indicators related to conflicts and militarization and UCMs. The ODA variable used only for OECD/DAC and HICs with available data came from third-party sources.

The influence of missing data is limited in our assessment and, where it did occur, we had a strategy in place. We managed to compile data for all 193 UN member states, except for two variables: Participation in conflicts and militarization and Official Development Assistance. Because we could not find any evidence of recent military interventions made by one of these countries and external sources suggest that, when available, most of these countries have low levels of military expenditure (<1.5 percent of GDP), we imputed a perfect score on “Participation in conflicts and militarization” to Barbados, Antigua and Barbuda, Maldives, Fiji, Belize, Saint Vincent and the Grenadines, the Bahamas, St. Lucia, Suriname, Cabo Verde, Luxembourg, Malta, Seychelles, Samoa, Grenada, St. Kitts and Nevis, Brunei Darussalam, Vanuatu, Sao Tome and Principe, Comoros, Liechtenstein, Monaco, San Marino, Dominica, Kiribati, Solomon Islands, Andorra, Tonga, Marshall Islands, Tuvalu, Palau, Nauru, and Micronesia. We only considered Official Development Assistance (ODA) for countries with available data in the OECD Development Assistance Committee (DAC) portal.

This normalization method mirrors the method used in the SDG Index (Sachs et al. 2023). The min-max formula was preferred to the Z-score transformation to enable the results to be interpreted as the distance to full country support for UN-based multilateralism (instead of distance to the mean), and because some of the variables were partly skewed. It also had the advantage of simplicity. Maximum values correspond to technical optimums, for instance, full participation in UN organizations or ratification of all major treaties. Maximum values for ODA and UNGA votes with the majority were set, respectively, to 0.8 percent of GNI and 95 percent. Minimum values corresponded to the lowest 2.5th percentile in the distribution (rounded), except for UCMs where there was one significant outlier within the lowest 2.5th percentile. For UCMs, the minimum value corresponded to the lowest percentile plus one standard deviation. Censoring values at the lowest 2.5th percentile is a standard threshold used for building composite indices and treating outliers (OECD and JRC 2008). Skewness and kurtosis tests were conducted to verify the shape of the distribution. Some variables such as UCMs, UN membership, and the payment of UN contributions were more skewed, which reflects the fact that most countries do not use UCMs, participate in all or most UN organizations, and pay their dues to the UN.

We tested the sensitivity of our results to the weighting scheme (using equal weights for all six variables) and aggregation method (using geometric mean). Detailed tables are available in the SI, including median rank changes for countries with a population of 1M and above (and all countries). Overall, the sensitivity tests suggest that the UN-Mi is quite robust—differences of 11 ranks can be interpreted with confidence using the reduced sample—and very robust at the top and bottom of the distribution. The scores of some small countries, including San Marino, Saint Vincent and the Grenadines, Sao Tome and Principe, the Solomon Islands, and Vanuatu tend to be more sensitive to methodological choices driven notably by low values on the membership and/or payment of UN contributions’ variables. Median rank changes are systematically below 10 percent of the total sample.

Because our goal is to focus on structural trends, and less on year-on-year changes, we computed average results over time by decade. We focus on 58 early members of the United Nations (countries that joined the UN between 1945 and 1950).

Due to data gaps over time, adjustments were made to compute the longitudinal data set of countries’ support of UN-based multilateralism over time. The UN membership focuses on a subset of seven organizations (instead of 24 in the cross-sectional analysis). These are UNESCO, WHO, IMF, UNIDO, WB Group, World Tourism Organization, and WTO. Country scores correspond to the total number of membership years divided by the maximum possible number of years for which countries could be members of these organizations in each decade. As such it rewards membership over multiple years. The UCM variable captures new UCMs introduced by decade. The treaties variable focuses on a more comprehensive list of 152 UN instruments mainly conventions and agreements (including, for instance, the Convention on the Abolition of Slavery and the Paris Climate Agreement) and captures the cumulative number of treaties ratified during each decade. Regional and expired legal instruments were excluded. The Global Peace Index has been available only since 2008, we therefore used military expenditure from SIPRI as our proxy for participation in conflicts and militarization. ODA data have been available since the 1960s from the OECD database. We could not find longitudinal data to track whether countries contributed their fair share to the UN annual budget and whether these contributions were provided without significant delays. The variable on UNGA votes corresponds to the average number of votes aligned with the vote of the international majority by decade.