Multiple Independently-targetable Reentry Vehicle. A ballistic missile equipped with multiple warheads that strike different targets. First, a PBV (Post-Boost Vehicle) loaded with warheads and reentry vehicles is launched. When the PBV reaches high altitude, reentry vehicles loaded with warheads are launched one by one at staggered speeds and angles. In short, the PBV acts as a secondary missile launcher.
Technology for developing small nuclear warheads is necessary for the development of MIRVs. For that reason, it is through that only a few nations, such as the US, possess MIRVs.
The ballistic launch Metal Gear is a weapon that brought to fruiting the principle behind MIRV in the 1970s. This particular Metal Gear flies on a ballistic orbit to reach its destination. The design concept focused on a Metal Gear loaded with a large volume of nuclear warheads which is dropped by parachute to execute ground-to-ground nuclear strikes.