In the middle of the 20th century, nations were racing to develop nuclear weapons, and the prospect of nuclear warfare cast a dark shadow on humanity, threatening its very existence.

Now, thanks to the Nuclear Non-Proliferation Treaty, that grim future never came to pass. The number of nations with nuclear weapons remains very small, and the number of nuclear arms worldwide has gone down.

“The NPT has become the cornerstone of the nuclear nonproliferation regime, reinforcing international peace and security, and preventing the further spread of nuclear weapons,” President Obama said on the treaty’s 45th anniversary. “Global nuclear stockpiles are at their lowest levels since the 1950s.”

The treaty, which entered into force on March 5, 1970, is the only internationally binding agreement aimed at curbing nuclear proliferation. With 190 members, it has the broadest support of any arms control treaty in history.

Countries that joined the NPT agree to take these actions:

  • Stop the spread of nuclear weapons.
  • Promote cooperation in the peaceful uses of nuclear energy.
  • Pursue good-faith negotiations toward nuclear disarmament.

“The United States is fully committed to continuing to fulfill its own treaty obligations, as well as to strengthening the global nuclear nonproliferation regime,” Secretary of State John Kerry said.

The Ninth Review Conference of the NPT will open in New York on April 27. Countries that are party to the NPT meet every five years to assess its implementation and discuss how to meet future challenges.