 The boats are capable of deploying with a maximum of 192 independently targetable warheads, or MIRVs, with immediate readiness to fire.However, as a result of a decision taken by the 1998 Strategic Defence Review this was reduced to 48 warheads with a readiness to fire reduced 'to days rather than minutes'.Furthermore, the total number of warheads maintained by the United Kingdom was reduced to approximately 200, with a total of 58 Trident missiles.