Someone is finally putting conventional warheads on an ICBM. The U.S. Navy is moving forward on this, after decades of it being talked about in several countries. This is part of a new strategy by the United States to be able to respond within hours to a threat, or opportunity, anywhere on the planet. The navy is taking the three ton warhead of the Trident D-5 SLBM (Sea Launched Ballistic Missile) and fitting it with non-nuclear weapons. This could be anything from a dozen or so SDBs (250 pound GPS guided smart bombs), to a single bunker busting weapon. One major design obstacle is the high re-entry speed of the Trident warhead (over 20,000 kilometers an hour). For sub-munitions (like the SDB), you have to get them slowed down enough so their guidance systems can work. Normally, SDBs are dropped from an aircraft traveling at less than a thousand kilometers an hour. For a bunker buster type bomb, you could use the high speed to advantage (in smashing through the roof of the bunker.) In any event, this type of weapon will be expensive. Currently, Trident D-5 SLBMs cost $66 million each.