- At first blush, it might seem entirely natural for the Pentagon and its troops to play a big role in protecting America's homeland from terrorist attacks.
After all, it is the Department of Defense. And it controls the world's best-trained, best-equipped military. Indeed, since Sept. 11, it has beefed up domestic involvement - such as assisting with air patrols above US cities and lending troops to strapped agencies like the Customs Service.
But the Pentagon is now trying to formalize a muscular domestic role for the first time in its history - by setting up a new homeland command called NORCOM by October. And it's running into a thicket of tough issues.
Some are core questions about democracy that have been debated since the nation's founding: Can a shoot-to-kill military patrol native soil without becoming a kind of occupying force that intimidates or mistreats citizens?
Others are purely logistical. The Pentagon has few troops available - and homeland defense is mostly handled by federal, state, and local law-enforcement. So what kind of power will NORCOM have if it's essentially troopless?
All in all, "It's going to be an organizational nightmare," says Loren Thompson, a military analyst at the Lexington Institute in Arlington, Va. That's partly because it involves meshing "a military that's deeply ambivalent about getting involved" with "scores of federal agencies, 50 state governments, thousands of state and local law-enforcement groups."
YET so far, there's consensus on at least a few things. Joint Chiefs Chairman Richard Myers told Congress recently the new command will have at least three missions:
Overseeing the North American Aerospace Defense Command (NORAD) which tracks hostile aircraft and any incoming intercontinental missiles from inside a Colorado mountain bunker.
Responding to natural disasters by setting up radio broadcasting and security - which the Army already does.
Responding to security needs in chemical, biological, nuclear, or other attacks.
NORCOM will be headed by a four-star general who will join the Pentagon's five other regional commanders who control all US troops in Europe, the Pacific, Latin America, the Mideast, and South Asia.
The size and scope of the mission are still being forged, say observers. To provide full-scale homeland defense could mean taking on other missions: protecting against a cruise-missile attack from the waters off the US, disrupting cyber attacks, foiling attempts to smuggle in chemical or biological weapons, even fighting the drug war or keeping out illegal aliens.
If the Pentagon takes on some or all of these missions, "it would very much be a case of breaking new ground with this command," says Andrew Krepinevich of the Center for Strategic and Budgetary Analysis. But any domestic military presence raises tough questions and uncomfortable memories.
The checkered history of domestic military involvement includes the 1999 killing of an American teenage shepherd near the US-Mexico border by Marines on a drug-interdiction mission, which deeply embarrassed the Pentagon.
Most famously, thousands of federal troops enforced laws in the post-Civil War South. This led to the Posse Comitatus Act of 1878, which bars the military from doing domestic law-enforcement.
Tossing out this law - or testing its limits in a major way - is "without precedent among democracies," and is akin to the way weak South American nations use troops to secure rebel-controlled provinces says Caleb Carr, a military historian.
To date, the courts have interpreted Posse Comitatus to mean the military can only have a "passive" role in domestic activities. This frequently means US troops serve in support roles - and don't carry weapons.
Indeed, NORCOM seems to be headed for a low-profile role.
NORAD, for instance, is but a shadow of its cold-war self. In 1958, it had 5,800 fighter jets at its command. On Sept. 10, it had just 20 - although, since then, many more have been added.
And the Joint Forces Command - from which NORCOM will get much of its terror-response strength - has just 2,300 people.
THE question, then, is: Is a general with few troops really a general? The NORCOM commander may have to be more of an arm-twisting diplomat than a military task master - and show deference to state and local agencies.
NORAD, for instance, must receive formal requests from the Federal Aviation Administration before monitoring domestic airliners. And, in general, it's unclear under what circumstances NORCOM would supercede state and local authorities.
One possible way to give NORCOM some actual resource strength, experts say, could be the National Guard. "They were born for this mission," says Mr. Krepinevich. Combining the Guard's 460,000 troops - who are familiar with their local and state communities - with the resources and centralization of a Pentagon command could be ideal. But so far the Guard is reluctant. Its commanders - who often see themselves as the military's poor stepchildren - are reluctant to get involved in what they see as a lesser mission compared with bigger overseas assignments,says Krepinevich.
It's just one of the many issues needing clarification by October.