“Hair-trigger alert” is a U.S. military policy that enables the rapid launch of nuclear weapons. Missiles on hair-trigger alert are maintained in a ready-for-launch status, staffed by around-the-clock launch crews, and can be airborne in as few as ten minutes.
The hair-trigger policy has its roots in the Cold War. Military strategists feared a “bolt from the blue” Soviet first strike, involving hundreds or thousands of nuclear weapons that would compromise our ability to retaliate. By keeping land-based missiles on hair-trigger alert—and nuclear-armed bombers ready to take off—the United States could launch vulnerable weapons before they were hit by incoming Soviet warheads. This helped ensure retaliation, and was seen as a deterrent to a Soviet first strike—a concept known as “mutually-assured destruction,” or MAD.
Submarines, which can’t be targeted when at sea, also kept weapons on hair-trigger alert. The decision to launch any nuclear weapon was based on information from radars and satellites, and remains so today.
The United States no longer keeps its bombers armed and ready to take off. But even though a Russian first-strike is not a credible risk, the United States still keeps its 450 silo-based nuclear weapons, and hundreds of submarine-based weapons, on hair-trigger alert. Thousands more—around 3,500 total—are deployed on other submarines or bombers, or kept in reserve.