The Lisbon Protocol to the 1991 Strategic Arms Reduction Treaty[1] was a document signed by representatives of Russia, Belarus, Ukraine, and Kazakhstan that recognized the four states as successors of the Union of Soviet Socialist Republics and all of them assume obligations of the Soviet Union under the START I treaty.

Done at Lisbon on 23 May 1992, in five copies, each in the Belarusian, English, Kazakh, Russian, and Ukrainian languages, all texts being equally authentic.

[6] Both Belarus and Ukraine resisted full implementation of the protocol during the 1990s, wishing to retain a nuclear deterrent force or a diplomatic bargaining chip.

Like Kazakhstan, Ukraine eventually agreed to surrender its nuclear weapons in exchange for security guarantees, military aid, financial assistance, and compensation from the United States and Russia.

[6] Implementation of the Lisbon Protocol was complete when both Belarus and Ukraine had surrendered their nuclear weapons to Russia by the end of 1996.

[9] The Lisbon Protocol provided that Ukraine equally with all its parties including the United States becomes a participant of the Strategic Arms Reduction Treaty and has to ratify it.

After signing the protocol, on 1 October 1992 President Leonid Kravchuk declared at the 46th UN General Assembly Ukraine's intent to acquire the status of non-nuclear state.