North Korean missile advances put new stress on US defenses

North Korea's newly demonstrated missile muscle puts Alaska within range of potential attack and stresses the Pentagon's missile defenses like never before.

Even more worrisome, it may be only a matter of time before North Korea mates an even longer-range ICBM with a nuclear warhead. That would put all the United States at risk.

The Pentagon has spent tens of billions to develop what it calls a limited defense against missiles capable of reaching U.S. soil. But the system has never faced combat or been fully tested.

These defenses may come into play soon if North Korea continues toward nuclear-armed ICBMs.