Secretary of Defense Donald Rumsfeld has given the Navy go ahead to develop a conventionally armed Trident missile. Two dozen existing nuclear-armed submarine-launched missiles will be converted to carry conventional warheads. The missiles will then be assigned "global strike" missions to allow quicker preemptive attacks....This is serious. There's no way for any nation to determine where a particular warhead is headed, except by watching the missile come. So if a boat is in the Sea of Japan and starts firing ballistic missiles at North Korea, the Russians and the Chinese would have every reason to assume the missiles were heading their way.
Were the United States ever to use its new conventional Tridents, the firing would also flirt with accidental nuclear war. Ballistic missiles aimed at targets in North Korea, for example, might falsely signal to China or Russia that the United States was attacking them.
Never mind that the US has given every indication that it favours a military response to Chinese power. This is a serious danger, and the US is risking nuclear war.
And why? Cruise Missiles can deliver a warhead for more than a thousand miles at this point, and can be launched by submarine just as easily. So why this? My guess is the speed aspect - a ballistic missile is quite a bit faster than a Tomahawk missile.
But ask yourself why the speed would be critical. After all, the only reason you'd want to be able to respond that quickly is that you have immediate intelligence of a target that you want to hit. But given recent US mistakes when it comes to targeting (wedding parties, etc.) having the missile commanders cool their heels for a few minutes might not be a bad idea.