A Ballistic Missile’s warheads are attached to the missile (MIRV – Multiple Independent Reentry Vehicles.
Each of these is a Hydrogen Bomb with an explosive capacity of 300 Kt TNT. That means each one has 20 times the explosive power of the weapon that was dropped on Hiroshima. This missile (LGM-118 Peacekeeper) could carry up to 11 such missiles.
A missile with MIRVs can attack multiple targets simultaneously. These are re-entry vehicles because they reach outer space and re-enter the atmosphere at high speeds.