A Fleet Ballistic Missile (FBM) is a type of missile designed to be launched from submarines. These missiles are primarily used by naval forces to deliver nuclear warheads over long distances. The ability to launch from underwater provides strategic advantages, including stealth and mobility, making it difficult for adversaries to detect and target the submarines. FBMs are part of a country's nuclear deterrent strategy, ensuring that a retaliatory strike is possible even after a surprise attack. The most well-known FBM in service is the Trident II, which is used by the United States Navy and is capable of carrying multiple warheads.