An intercontinental ballistic missile, or ICBM, is a long-range (greater than 5,500 km or 3,500 miles) ballistic missile typically esigned for nuclear weapons delivery, that is, delivering one or more nuclear warheads. However, new designs contemplated by the United States envision a conventional or even inert (non-explosive) payload, relying on the great speed at impact to cause significant damage. Due to their great range and firepower, in an all-out nuclear war, submarine and land-based ICBMs would carry most of the destructive force, with nuclear-armed bombers the remainder.