The Pentagon next year will attempt to track and shoot down a maneuvering hypersonic missile flying up the U.S. East Coast, the first live demonstration of a layered defense the military has been racing to build against a class of weapons fielded by China and Russia. The test, part of a Missile Defense Agency effort code-named Project Maverick, would mark a significant step in U.S. efforts to counter hypersonic glide vehicles -- weapons that fly at more than five times...