Now that war between the U.S.-led coalition and Iraq is underway, we must take seriously Saddam Hussein's threat to unleash the full arsenal of terrorism against us wherever in the world we are to be found, including here at home: "America," he warns, "will swim in its own blood." Exaggeration? Maybe. But he and his coven of terrorists have had lots of practice and no known inhibitions. So what do we do about it?

The first thing we do is take the threat seriously -- not to the extent of tearing apart the fabric of our free and open society, nor of promiscuously suspending constitutional protections of the rights of citizens and resident foreign nationals, but seriously.

The second thing we do, if we're serious about the prospect of terrorist attack, is to call on the experts in the business of counter-terrorism. That means the FBI and local police, because terrorism by definition obliterates state boundaries. Moreover, we then grant our law enforcement professionals a reasonable amount of elbow room to do their jobs effectively and with the greatest chance for success.

What we do not do is fall prey to hysterical overreaction, either to the threat itself or to the quite routine, ordinary, even dull investigative techniques employed by the forces of counter-terrorism.

One of the most common of these investigative techniques is to ask people questions. And not just any old people, of course, but those who are in the best position to know something about the activity in question, or who might even engage in it themselves (whether willingly or underduress), or who might possess information about it (often without even suspecting its significance) -- precisely because of who they are, and the circles of their acquaintance, and their susceptibility to the pressures of, let us say, ethnic "solidarity" (also known as blackmail).

If the activity under investigation is Iraqi-sponsored terrorism against American targets, one very logical focus of such question-asking is the Arab-American community. Not because the local police or the FBI are anti-Arab, but because, in trying to head off potential terrorist attack, they go where the ducks may be or may seek sanctuary and support.

If anything, members of the Arab-American community are likely to be more the beneficiaries than the victims of effective counter-terrorism: they themselves need (and would receive) protection against the self-appointed vigilantes that terrorist atrocities might spawn.

All of which brings us to the ongoing FBI interview program within the Arab-American community -- and, even more, to the hysterical reaction it has provoked among those who style themselves the protectors of American civil liberties. The Post's editorial of Jan. 16 {"Singling Out Arab Americans"} mirrors these concerns and even conjures up images of the internment of Japanese-Americans during World War II.

It is true that all Americans are individuals under the law; but by choice of by circumstance most of us also are identified by groups. Given the limited counter-terrorism resources available to us in this country and the right of any American to simply say no to questions from law enforcement officers, the charge that Arab-American business and community leaders are being singled out for some sinister motive, or might even be candidates for internment camps, is -- to put it bluntly -- irresponsible. This overreaction to legitimate investigative technique ignores the duties and responsibilities of citizenship and demeans the professionalism of those whose job it is to defend the Constitution and all our citizens.

Be it tighter security at our borders, or eliciting important and timely information from those who may be in a position to help prevent terrorism, any democratic government and free society must rely on the cooperation of its citizens. The world situation and the imminent threat of terrorism require action. The challenge is to respond in a reasonable way -- like, for example, the FBI interview program. Charles M. Lichenstein is a former U.S. deputy representative to the U.N. Security Council.

Paul M. Joyal is the former director of security of the Senate Select Committee on Intelligence.