What is Launch on warning?

Launch on warning , or fire on warning, is a strategy of nuclear weapon retaliation that gained recognition during the Cold War between the Soviet Union and the United States. With the invention of intercontinental ballistic missiles , launch on warning became an integral part of mutually-assured destruction theory. Under the strategy, a retaliatory strike is launched upon warning of enemy nuclear attack while its missiles are still in the air and before detonation occurs. US land-based missiles can reportedly be launched within 5 minutes of a presidential decision to do so and submarine-based missiles within 15 minutes.