It was one of the worst ideas of the George W. Bush administration. In the early 2000s, the U.S. Defense Department under Defense Secretary Donald Rumsfeld proposed fielding an arsenal of non-nuclear ballistic missiles meant for quickly targeting fleeting terrorist targets, such as training camps and leadership meetings. The so-called “Prompt Global Strike” initiative initially envisioned replacing the nuclear warheads with conventional explosives on existing Navy Trident ballistic missiles or Minuteman missiles belonging to the Air Force.
It was a very, very bad idea, for one very simple reason. To the early-warning radars of other nuclear powers (Russia and China, especially) a non-nuclear ballistic missile launched from the United States would look just like a nuclear version — and could spark World War III. “The launch of such a missile could provoke a full-scale counterattack using strategic nuclear forces,” then-Russian President Vladimir Putin said in response to the plan.
Bush wisely shelved the Prompt Global Strike idea. Then, in 2010, the Barack Obama administration dusted it off.