NPR:
President Trump’s national security adviser, John Bolton, is in Moscow for a second day Tuesday, to discuss the U.S. intent to withdraw from the Intermediate-Range Nuclear Forces Treaty. The end of the 31-year old treaty is a sign that world powers may be returning to an arms race mentality.
But it’s not the only one. Over the past year the U.S., China and Russia have all stepped up efforts to develop a new kind of missile; a weapon that can fly faster and farther than almost anything in existence.
Known as a hypersonic weapon, it would travel at five times the speed of sound or more. It could strike at a target while evading missile defenses and hit almost without warning deep inside enemy territory.