DARPA Hypersonic FALCON HTV-2

Prompt Global Strike: The intercontinental ballistic missile is the only publicly acknowledged weapon capable of striking any point on the planet in less than an hour. Yet because Russia possesses defenses that would perceive the launch of an ICBM as the beginning of a nuclear war, launching even a non-nuclear ICBM is inadvisable. An alternative: hypersonic cruise missiles, which could travel at several times the speed of sound without appearing on radar as an existential threat. The Pentagon has at least five active hypersonic programs today.

Technologically, the precise, one-hour capability is not inconceivable. By leaving the Earth’s atmosphere and traveling at 15,000 mph, an intercontinental ballistic missile can reach any point in the world within 30 minutes.