The landmark agreement signed in 1965 to limit nuclear weapons is known as the Non-Proliferation Treaty (NPT). The treaty aimed to prevent the spread of nuclear weapons and promote peaceful uses of nuclear energy while furthering efforts toward disarmament. The NPT was initially opened for signature in 1968 and entered into force in 1970, being a pivotal moment in international relations during the Cold War. Nearly all countries in the world are now signatories, and the NPT remains a critical framework for addressing nuclear proliferation, although challenges and concerns about compliance and new nuclear states persist.