The long-planned shift in the Defense Department's role in homeland security was recently backed with funding and troop commitments after years of prodding by Congress and outside experts, defense analysts said.
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.
If funding continues, two additional teams will join nearly 80 smaller National Guard and reserve units made up of about 6,000 troops in supporting local and state officials nationwide. All would be trained to respond to a domestic chemical, biological, radiological, nuclear, or high-yield explosive attack, or CBRNE event, as the military calls it.
Military preparations for a domestic weapon-of-mass-destruction attack have been underway since at least 1996, when the Marine Corps activated a 350-member chemical and biological incident response force and later based it in Indian Head, Md., a Washington suburb. Such efforts accelerated after the Sept. 11 attacks, and at the time Iraq was invaded in 2003, a Pentagon joint task force drew on 3,000 civil support personnel across the United States.
In 2005, a new Pentagon homeland defense strategy emphasized "preparing for multiple, simultaneous mass casualty incidents." National security threats were not limited to adversaries who seek to grind down U.S. combat forces abroad, McHale said, but also include those who "want to inflict such brutality on our society that we give up the fight," such as by detonating a nuclear bomb in a U.S. city.
In late 2007, Deputy Defense Secretary Gordon England signed a directive approving more than $556 million over five years to set up the three response teams, known as CBRNE Consequence Management Response Forces. Planners assume an incident could lead to thousands of casualties, more than 1 million evacuees and contamination of as many as 3,000 square miles, about the scope of damage Hurricane Katrina caused in 2005.
Last month, McHale said, authorities agreed to begin a $1.8 million pilot project funded by the Federal Emergency Management Agency through which civilian authorities in five states could tap military planners to develop disaster response plans. Hawaii, Massachusetts, South Carolina, Washington and West Virginia will each focus on a particular threat -- pandemic flu, a terrorist attack, hurricane, earthquake and catastrophic chemical release, respectively -- speeding up federal and state emergency planning begun in 2003.
Last Monday, Defense Secretary Robert M. Gates ordered defense officials to review whether the military, Guard and reserves can respond adequately to domestic disasters.
Gates gave commanders 25 days to propose changes and cost estimates. He cited the work of a congressionally chartered commission, which concluded in January that the Guard and reserve forces are not ready and that they lack equipment and training.
Bert B. Tussing, director of homeland defense and security issues at the U.S. Army War College's Center for Strategic Leadership, said the new Pentagon approach "breaks the mold" by assigning an active-duty combat brigade to the Northern Command for the first time. Until now, the military required the command to rely on troops requested from other sources.
"This is a genuine recognition that this [job] isn't something that you want to have a pickup team responsible for," said Tussing, who has assessed the military's homeland security strategies.
The American Civil Liberties Union and the libertarian Cato Institute are troubled by what they consider an expansion of executive authority.
Domestic emergency deployment may be "just the first example of a series of expansions in presidential and military authority," or even an increase in domestic surveillance, said Anna Christensen of the ACLU's National Security Project. And Cato Vice President Gene Healy warned of "a creeping militarization" of homeland security.
"There's a notion that whenever there's an important problem, that the thing to do is to call in the boys in green," Healy said, "and that's at odds with our long-standing tradition of being wary of the use of standing armies to keep the peace."
McHale stressed that the response units will be subject to the act, that only 8 percent of their personnel will be responsible for security and that their duties will be to protect the force, not other law enforcement. For decades, the military has assigned larger units to respond to civil disturbances, such as during the Los Angeles riot in 1992.
U.S. forces are already under heavy strain, however. The first reaction force is built around the Army's 3rd Infantry Division's 1st Brigade Combat Team, which returned in April after 15 months in Iraq. The team includes operations, aviation and medical task forces that are to be ready to deploy at home or overseas within 48 hours, with units specializing in chemical decontamination, bomb disposal, emergency care and logistics.
The one-year domestic mission, however, does not replace the brigade's next scheduled combat deployment in 2010. The brigade may get additional time in the United States to rest and regroup, compared with other combat units, but it may also face more training and operational requirements depending on its homeland security assignments.
Renuart said the Pentagon is accounting for the strain of fighting two wars, and the need for troops to spend time with their families. "We want to make sure the parameters are right for Iraq and Afghanistan," he said. The 1st Brigade's soldiers "will have some very aggressive training, but will also be home for much of that."
Although some Pentagon leaders initially expected to build the next two response units around combat teams, they are likely to be drawn mainly from reserves and the National Guard, such as the 218th Maneuver Enhancement Brigade from South Carolina, which returned in May after more than a year in Afghanistan.
Now that Pentagon strategy gives new priority to homeland security and calls for heavier reliance on the Guard and reserves, McHale said, Washington has to figure out how to pay for it.
"It's one thing to decide upon a course of action, and it's something else to make it happen," he said. "It's time to put our money where our mouth is."