Missile defense is a system, weapon, or technology involved in the detection, tracking, interception, and also the destruction of attacking missiles. Conceived as a defense against nuclear-armed intercontinental ballistic missiles (ICBMs), its application has broadened to include shorter-ranged non-nuclear tactical and theater missiles.
China, France, India, Iran, Israel, Italy, Russia, Taiwan, the United Kingdom and the United States have all developed such air defense systems.
Under the Manhattan Project, the United States was the first country to manufacture nuclear weapons and is the only country to have used them in combat, with the bombings of Hiroshima and Nagasaki in World War II against Japan. In total it conducted 1,054 nuclear tests, and tested many long-range nuclear weapons delivery systems.
The United States currently deploys 1,770 warheads, mostly under Strategic Command, to its nuclear triad: Ohio-class submarines with Trident II submarine-launched ballistic missiles, silo-based Minuteman III intercontinental ballistic missiles, and B-2 Spirit and B-52 Stratofortress bombers armed with B61 and B83 bombs and AGM-86B cruise missiles. The US maintains a limited anti-ballistic missile capability via the Ground-Based Interceptor and Aegis systems. The US plans to modernize its triad with the Columbia-class submarine, Sentinel ICBM, and B-21 Raider, from 2029.
The Arleigh Burke class of guided-missile destroyers (DDGs) is a United States Navy class of destroyers centered around the Aegis Combat System and the SPY-1D multifunction passive electronically scanned array radar. The class is named after Arleigh Burke, an American destroyer admiral in World War II and later Chief of Naval Operations. With an overall length of 505 to 509.5 feet (153.9 to 155.3Â m), displacement ranging from 8,300 to 9,700 tons, and weaponry including over 90 missiles, the Arleigh Burke-class destroyers are larger and more heavily armed than many previous classes of guided-missile cruisers.
These warships are multimission destroyers able to conduct antiaircraft warfare with Aegis and surface-to-air missiles; tactical land strikes with Tomahawk missiles; antisubmarine warfare (ASW) with towed array sonar, antisubmarine rockets, and ASW helicopters; and antisurface warfare (ASuW) with ship-to-ship missiles and guns. With upgrades to their AN/SPY-1 radar systems and their associated missile payloads as part of the Aegis Ballistic Missile Defense System, as well as the introduction of the AN/SPY-6 radar system, the class has also evolved capability as mobile antiballistic missile and antisatellite platforms.
The Anti-Ballistic Missile Treaty, also known as the ABM Treaty or ABMT, was a 1972 arms control treaty between the United States and the Soviet Union on the limitation of the anti-ballistic missile (ABM) systems used in defending areas against strategic ballistic missiles, which are used to deliver nuclear weapons. It was intended to reduce pressures to build more nuclear weapons to maintain deterrence. Signed in 1972, it was in force for the next 30 years. Citing purported risks of nuclear blackmail from a rogue state, the United States under the George W. Bush administration unilaterally withdrew from the treaty in June 2002, leading to its termination. In ICBM defense, the US has subsequently operated the Ground-Based Midcourse Defense ABM system based in Alaska and California, as well as the sea-based Aegis Ballistic Missile Defense System. Russia maintains the A-135 ABM system around Moscow, and has developed the S-500 missile system.
Under the terms of the original 1972 treaty, each party was limited to two ABM complexes, one for the nation's capital and one for an intercontinental ballistic missile silo field. Each ABM complex was limited to 100 anti-ballistic missiles and their launchers, two phased-array radars, and 18 smaller radars for early-warning. ABM missiles that were not static and ground-based were prohibited. In 1974, the limit was reduced to just a single ABM complex. The USSR chose to deploy the A-35 system around its capital Moscow, the US elected to deploy the Safeguard Complex around its ICBM fields of the Twentieth Air Force, although this was only operational for a year from 1974 to 1975. A 1997 treaty addendum permitted "theater missile defense": anti-ballistic missiles used against theatre ballistic missiles, as long as they were not tested against targets with velocities over 5 km/s, typical of ICBM terminal phase. Also in 1997, five years after the dissolution of the Soviet Union, its former member states Belarus, Kazakhstan, Russia, and Ukraine were established as successors to the USSR within the treaty, with one ABM system permitted between them.