Pentagon to Detail Troops to Bolster Domestic Security

There are critics of the change, in the military and among civil liberties groups and libertarians who express concern that the new homeland emphasis threatens to strain the military and possibly undermine the Posse Comitatus Act, a 130-year-old federal law restricting the military's role in domestic law enforcement.

But the Bush administration and some in Congress have pushed for a heightened homeland military role since the middle of this decade, saying the greatest domestic threat is terrorists exploiting the proliferation of weapons of mass destruction.

Before the terrorist attacks of Sept. 11, 2001, dedicating 20,000 troops to domestic response -- a nearly sevenfold increase in five years -- "would have been extraordinary to the point of unbelievable," Paul McHale, assistant defense secretary for homeland defense, said in remarks last month at the Center for Strategic and International Studies. But the realization that civilian authorities may be overwhelmed in a catastrophe prompted "a fundamental change in military culture," he said.

The Pentagon's plan calls for three rapid-reaction forces to be ready for emergency response by September 2011. The first 4,700-person unit, built around an active-duty combat brigade based at Fort Stewart, Ga., was available as of Oct. 1, said Gen. Victor E. Renuart Jr., commander of the U.S. Northern Command.