North Korea has made significant strides in its attempt to acquire a strategic nuclear deterrent. In 2017, it tested intercontinental ballistic missiles (ICBMs) and completed a series of nuclear test explosions. These may provide North Korea with the technical foundation to deploy a nuclear-armed ICBM capable of striking the United States. The Ground-based Midcourse Defense (GMD) missile defense system is intended to deter North Korean nuclear coercion and, if deterrence fails, to defeat a limited North Korean attack. Despite two decades of dedicated and costly efforts, however, the GMD system remains unproven and unreliable. It has not demonstrated an ability to defeat the relatively simple and inexpensive countermeasures that North Korea can field. The GMD system has suffered persistent delays, substantial cost increases, and repeated program failures because of the politically motivated rush to deploy in the 1990s. But GMD and other U.S. missile defense efforts have provoked serious concerns in Russia and China, who fear it may threaten their nuclear deterrents. Diplomacy and deterrence may reassure Russia and China while constraining North Korea's nuclear program. An alternate airborne boost-phase intercept system may offer meaningful defense against North Korean missiles without threatening the Russian or Chinese deterrents.

Pakistan has introduced a new battlefield nuclear weapon, Nasr, into its arsenal. Nasr, a short-range ballistic missile, was first flight-tested in 2011. Pakistani leaders have declared that the weapon is meant to deter India from executing its Cold Start war doctrine. The doctrine was conceived by members of India's army and its strategic community in 2004 as a solution to perceived operational shortcomings of the army in responding to major terrorist incidents involving Pakistanis. It recommends the positioning of smaller army units at the international border with the capability to rapidly invade Pakistan and occupy narrow slices of territory, while denying Pakistan the ability to anticipate the attack and to immediately assemble a counterattack force. The Cold Start war doctrine, however, has since been publicly disavowed by the Indian government, and the Indian army has not reorganized or equipped its troops in a manner consistent with the doctrine. Further, the use of battlefield nuclear weapons inside Pakistan or near the densely populated border regions could potentially cause civilian casualties in the tens of thousands. These factors should dissuade Pakistan from deploying the Nasr missile.