When a guerrilla movement opposing Portuguese rule in Guinea-Bissau issued a unilateral declaration of independence in September 1973, it created a dilemma for Portugal's allies in the North Atlantic Treaty Organization (NATO). Although Britain, like other NATO countries, wanted to keep Portugal within the alliance, British officials were exasperated by the Portuguese regime's refusal to let go of its colonies in Africa. When the United Nations (UN) took up the issue of Guinea-Bissau, Britain came under intense pressure from Portugal to proffer its support. Declassified documents from the British National Archives underscore the difficulties that ensued. British officials were mindful of their relationship with Portugal, but they were unsure of the intentions of the other Western permanent members of the UN Security Council and were worried about damaging Britain's broader position in Africa. This dilemma was not resolved until April 1974 when a military coup in Lisbon led to the Portuguese withdrawal from Guinea-Bissau.