U.S. law enforcement officials scrambling to stop terrorist attacks before they happen may have overlooked a hole in their lines of defense right here on American soil - student terrorists.

Iraq's Saddam Hussein repeatedly hinted that a clandestine war waged by terrorists would follow any attack by the United States on Iraq. Airports beefed up their security, as did border inspectors. But there is little that can be done about Saddam loyalists who are already in the United States legally.More than 5,000 Iraqis are currently in the United States on student visas. Not all Iraqi students are terrorists-in-the-making. Most are simply students minding their own business and agonizing about the unwanted war, just as Americans are.

But if there was one Iraqi in the United States on a student visa who had more than exams on the mind, the Immigration and Naturalization Service would be hard pressed to find out about it. In many cases, the INS doesn't even know if the people here on student visas are really in school. Ever since the Iran hostage crisis of 1980, universities have been required to submit quarterly reports on the status of their foreign students. But those reports are spotty, outdated and unreliable.

A high-level INS source told us in 1989 that the INS had tried to find Libyan students after the U.S. bombing of Libya, but "the system was so corrupted we couldn't use it."

When Iraq invaded Kuwait in August, the INS ordered a search of its computer data base looking for Iraqis living in the United States. The information from the search was apparently passed on to the FBI.

But it probably didn't come close to covering the territory. "It's virtually impossible for us to track that many people. Each of us would have to follow a hundred students," INS spokesman Duke Austin told our reporter Paul Parkinson. Even if the INS and the FBI could find all of the Iraqis living in the United States, it's questionable whether they could, or should, do anything with that information. The American respect for the rights of the individual, even the foreign individual, runs deep. Americans get nervous about threats of terrorism, but they also get nervous when the FBI starts knocking on doors.

While Iraqis have done their best to maintain a low profile in the United States in the days since the Aug. 2 invasion, more than 1,200 Kuwaiti students living here volunteered for duty in the Persian Gulf.

The Pentagon accepted 300 of them and put them through intensive special training at Fort Dix near Trenton, N.J. Their assignment was to act as scouts and translators on the front lines.

Although they are not recognized as members of the U.S. military, they were trained to play a major role in any ground-force action, going ahead of U.S. troops, undercover, into Kuwait to pinpoint the location of Iraqi troops. They were all given the rank of sergeant in the Kuwaiti armed forces. Several middle-aged Kuwaiti businessmen were also chosen to be part of the contingent.