A submarine-launched ballistic missile (SLBM) is a ballistic missile capable of being launched from submarines. Modern variants usually deliver multiple independently targetable reentry vehicles (MIRVs) each of which carries a nuclear warhead and allows a single launched missile to strike several targets. Submarine-launched ballistic missiles operate in a different way from submarine-launched cruise missiles. Modern submarine-launched ballistic missiles are closely related to intercontinental ballistic missiles, and in many cases SLBMs and ICBMs may be part of the same family of weapons.