The Lisbon Protocol to the START I Treaty (Protocol to the Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Reduction and Limitation of Strategic Offensive Arms) was signed on May 23, 1992. After the breakup of the Soviet Union, this protocol called for Belarus, Kazakhstan, Russia and Ukraine to become parties to the START I Treaty, with those states promising to join the NPT as non-nuclear weapon states.
