High-alert nuclear weapon

High-alert nuclear weapon(s) commonly refers to a launch-ready ballistic missile(s) armed with a nuclear warhead(s) whose launch can be ordered (through the National Command Authority) and executed (via a nuclear command and control system) within 15 minutes or less. This can include any weapon system capable of delivering a nuclear warhead in this time frame.

Virtually all high-alert nuclear weapons are possessed by the U.S. and Russia. Both nations use automated command and control systems in conjunction with their early warning radar and/or satellites to facilitate the rapid launch of their land-based intercontinental ballistic missiles (ICBMs) and some submarine-launched ballistic missiles (SLBMs). Fear of a "disarming" nuclear first-strike that would destroy their command and control systems and nuclear forces led both nations to develop "launch-on-warning" capability, which requires high-alert nuclear weapons able to launch on a 30-minute (or less) tactical warning, the nominal flight time of ICBMs traveling between the U.S. and Russia.

A definition of "high-alert" requires no specific explosive power of the weapon carried by the missile or weapon system, but in general, most high-alert missiles are armed with strategic nuclear weapons with yields equal to or greater than 100 kilotons. The U.S. and Russia have for decades possessed ICBMs and SLBMs capable of being launched in only a few minutes.

The U.S. and Russia currently have a total of 900 missiles and 2581 strategic nuclear warheads on high-alert, launch-ready status. The total explosive power of these weapons is about 1185 Mt (megatons, or 1.185 billion tons of TNT equivalent explosive power).