The Anti-Ballistic Missile Treaty (ABM Treaty or ABMT) was a treaty between the United States and the Soviet Union on the limitation of the anti-ballistic missile (ABM) systems used in defending areas against missile-delivered nuclear weapons. Under the terms of the treaty, each party was limited to two ABM complexes, each of which were to be limited to 100 anti-ballistic missiles. Signed in 1972, it was in force for the next 30 years until the US unilaterally withdrew from it in June 2002.