Atomic bomb explosion in the Marshall Islands. National Archives.
Since entering into force in 1970, the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the NPT, has remained the cornerstone of the international nonproliferation regime. In creating a system of mutual responsibilities and an international taboo against the use or threat to use nuclear weapons, the NPT has proven largely successful in stemming proliferation.
But the nonproliferation regime faces new challenges: insufficient protections against the theft or sale of various nuclear materials in states of the former Soviet Union; nuclear black market activity such as the network operated by A.Q. Khan out of Pakistan; threats by North Korea to share nuclear technology with states or non-state actors hostile to the U.S.; and, most recently, violations of IAEA nuclear safeguard standards by Iran, a signatory of the NPT which is enriching uranium and has been accused of engaging in activities related to nuclear weapons research and design. Iran argues that it is making nuclear fuel for purely civilian purposes.
The threat of nuclear terrorism is producing additional challenges to the NPT regime, particularly in the areas of securing and safeguarding nuclear weapons material.
Many experts agree that some type of nonproliferation regime reform is necessary, particularly since certain states have interpreted the NPT as allowing them to acquire nuclear technologies that take them to the brink of acquiring an actual nuclear weapon without explicitly violating the treaty, sometimes referred to as a "breakout capability." Withdrawing from the NPT also carries no penalty, save possible ad hoc action taken by the U.N. Security Council.