US Navy Seeks Rapid-Strike Missile System

This idea caught my eye:

The US Navy is seeking funding to convert Trident nuclear submarine missiles to conventionally armed rapid-response weapons.

The plan calls for a missile arsenal that is capable of striking any target within 6000 miles of a patrolling submarine in under 24 minutes, with a guaranteed accuracy of less than 10 yards.

The "Prompt Global Strike" programme claims that even underground bunkers could be destroyed by solid-slug warheads plunging from space at high speed.

A second warhead consisting of flechettes – barbed shrapnel designed to shred vehicles, penetrate fuel tanks and kill anyone not under solid cover – could be developed to tackle surface targets.

At $30.9 million a piece and eight warheads per missile, that's almost $3.9 million per target serviced.