Anti-Ballistic Missile Treaty
The Anti-Ballistic Missile Treaty (ABM Treaty) was an agreement between the United States and the Soviet Union made on May 26, 1972. It was signed by Richard Nixon and Leonid Brezhnev. Its purpose was to limit the number of anti-ballistic missile sites in each country to just two sites. (Later limited by a new protocol to just one site, around the nation's capital.) It also made many restrictions on the upgrading of regular missiles to prevent them from being able to intercept strategic nuclear weapons. The idea was to prevent either nation from having a nationwide defense system against strategic nuclear weapons, lest one side gain the ability to do a first strike. The ABM treaty was in effect for roughly 30 years, until President George W. Bush withdrew the US in 2002.
It turned out that basis of the treaty was flawed, relying as it did on the false doctrine of moral equivalence. Although the US has been branded imperialist, it has not been in the habit of destroying the sovereignty of other countries to expand its empire; that is what USSR did (see Soviet Empire). Also, as the US (chiefly under President Ronald Reagan) made progress with its Strategic Defense Initiative, the Soviets never did launch a pre-emptive strike, while of course the US never launched a first strike. The whole thing ended peacefully.
This article defines what an ABM system is. It includes all ABM missiles, launchers, and radar. It also encompasses operation, decommissioned, and prototype systems, as well as systems that are being built/repaired.
This article limits each contracting party to two ABM sites. One site may be around the nation's capital and another may be around an ICBM site of their choosing. These two sites must be at least 1,300 kilometers apart. Both sites are limited to a radius of 150 kilometers and each site may have no more than 100 missiles and 100 missile launchers.
Each party agrees not to develop any form of mobile ABM system. They also agree not to upgrade any ABM missile launchers in any way that would allow them to chamber more than one missile, or would allow for rapid reloading.
This article prevents the parties from upgrading standard missiles in any way that would allow them to act as anti-ballistic missiles. It also places limitations on each party's early warning radar systems.
This article states that the parties must dismantle all extra ABM systems, outside of those provided by in the treaty, in the shortest manner possible.
This article prohibits the parties from setting up ABM systems outside of their national borders. It also prohibits the parties from giving ABM technology to third party nations.