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.