The ABM Treaty, was signed by the United States and the former Soviet Union, constrained strategic missile defenses to a total of 200 launchers and interceptors per country. The treaty was modified in 1974, reducing the number of ABM deployment areas permitted for each side from two to one and the number of ABM launchers and interceptors from 200 to 100. However, on June 13, 2002, the United States officially withdrew from the ABM Treaty in order to pursue the development of a missile defense system.