This book explores conventional prompt global strike and long-range ballistic mission options. Prompt global strike (PGS) would allow the United States to strike targets anywhere on earth with conventional weapons in as little as an hour. This capability may bolster U.S. efforts to deter and defeat adversaries by allowing the United States to attack high-value targets or "fleeting targets" at the start of or during a conflict. Congress has generally supported the PGS mission, but it has restricted funding and suggested some changes in funding for specific programs. Many analysts believe that the United States should use long-range ballistic missiles armed with conventional warheads for the PGS mission. These weapons would not substitute for nuclear weapons in the U.S. war plan but would, instead, provide a "niche" capability, with a small number of weapons directed against select, critical targets which might expand the range of U.S. conventional options.