As used in this subchapter—

(1) the term “INF Treaty” means the Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Elimination of Their Intermediate-Range and Shorter-Range Missiles (signed at Washington, December 8, 1987);

(2) the term “OSIA” means the On-Site Inspection Agency established by the President, or such other agency as may be designated by the President to carry out the on-site inspection provisions of the INF Treaty;

(3) the term “Peaceful Nuclear Explosions Treaty” means the Treaty Between the United States of America and the Union of Soviet Socialist Republics on Underground Nuclear Explosions for Peaceful Purposes (signed at Washington and Moscow, May 28, 1976); and

(4) the term “Threshold Test Ban Treaty” means the Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Underground Nuclear Weapons Tests (signed at Moscow, July 3, 1974).