What is hair-trigger alert?

“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.

Learn more:

Why is hair-trigger alert dangerous?

Hair-trigger alert is quick-launch option for our nuclear weapons.

Photo: Sam Howzit

Hair-trigger alert increases the risk of an accidental nuclear missile launch, or a deliberate launch in response to a false warning. The results of such a launch would be catastrophic: modern weapons are many times more powerful than the bombs that destroyed Hiroshima and Nagasaki, capable of killing millions of people with a single warhead.

Interactive feature on nuclear close calls

Years of near misses highlight the problems with US nuclear policy. Spin our wheel of near misfortune >

The risks of hair-trigger alert aren’t theoretical. A training tape was once misinterpreted as reality, initiating the steps needed to launch an attack. A defective computer chip once falsely reported an incoming attack at a time of extremely high tensions. And radar and satellite systems have both delivered false positives, giving decision makers limited time to sort out the truth.

Removing U.S. land-based missiles from hair-trigger alert would immediately reduce these risks. It would also encourage reciprocity from Russia, increasing our safety further. And because the United States deploys missiles on submarines—which are invulnerable to attack—we would maintain a nuclear deterrent against any first strike.

Learn more:

How can we end hair-trigger alert?

Barack Obama recognized the riskiness of hair-trigger alert while campaigning.

Photo: Campaign for Barack Obama

All U.S. missile silos have a safety switch that is used to prevent a launch of the missile when, for example, maintenance crews are in the silo. The United States could remove its land-based missiles from hair trigger alert by turning this switch to the safe position in each silo.   

As Commander-in-Chief, President Obama can independently end hair-trigger alert. Like George W. Bush before him, he recognized the importance of doing so during his campaign—but he hasn’t acted.

You can help. Remind the president of his promise to end hair-trigger alert and help prevent a nuclear catastrophe.

Learn more:

We Need Your Support
to Make Change Happen

We can increase global security and take U.S. nuclear weapons off hair-trigger alert—but not without you. Your generous support helps develop science-based solutions for a healthy, safe, and sustainable future.