The latest FBI terror warning is that al Qaeda may be planning to attack passenger trains, “possibly using operatives who have a Western appearance.” This is the second terrorist warning in the last two weeks. Previously, FBI Director Robert Mueller said that terrorists could strike soon while offering little assurance that his agency could thwart the next attack. And CIA Director George Tenet said that it was “unambiguous” that al Qaeda intends to strike the United States.

Meanwhile, the homeland security advisory system — which is supposed to “provide a comprehensive and effective means to disseminate information regarding the risk of terrorist acts to … the American people” — remains on yellow alert signifying a “significant risk of terrorist attacks.” One would think that the advisory system would bear some resemblance to actual warnings. Not so.

Since its inception in March, the color-coded homeland security advisory system has been nothing but government sound and fury signifying much of nothing.

For six months the alert level was flat-lined on yellow. This despite all manner of warnings about possible terrorist attacks in the United States. Warnings and dire pronouncements were at a crescendo in May. U.S. intelligence sources reported that Islamic terrorists were planning an attack on nuclear power plants on the 4th of July. Vice President Cheney warned that another terrorist attack was “almost certain.” Mueller said that suicide bombers like those who have attacked Israel are “inevitable,” and the FBI asked apartment owners to report any suspicious activity. Director of Homeland Security Tom Ridge said a future terrorist attack was “not a question of if, but a question of when.”

Secretary of Defense Donald Rumsfeld echoed Ridge, stating that the “question is not if, but when, where, and how” another terrorist attack will occur. Capping those warnings, the FBI alerted New York City authorities about possible terrorist attacks against city landmarks, such as the Statue of Liberty and the Brooklyn Bridge. And the Department of Transportation issued a warning about possible attacks against subway and rail systems. None of this, however, was enough to change the alert status from yellow.

The only time the alert level has changed was on the anniversary of the Sept. 11 terrorist attacks. But the change to “orange” signifying a “high risk of terrorist attacks” had absolutely nothing to do with any threats to homeland security. Attorney General John Ashcroft said the heightened terror alert was prompted by “specific intelligence” pointing to threats against U.S. interests abroad-yes, overseas — in South Asia and the Middle East. President Bush admitted, “We have no specific threat to America.” So why increase the homeland security alert level and thus the public’s level of fear and anxiety?

After two weeks, the alert level was lowered again to yellow. White House spokesman Ari Fleischer said that keeping the alert status at “an artificially high level” would undermine the system. But if there was no real threat to the U.S. homeland when the threat level was first raised, then by definition it was raised to an artificially high level to begin with.

Even more absurd was a joint statement by Ashcroft and Ridge when the alert level was lowered: “Detained al Qaeda operatives have informed U.S. intelligence and law enforcement officials that al Qaeda will wait until it believes Americans are less vigilant and less prepared before it will strike again.” So lowering the alert status means we’re more vigilant and more prepared?

The sad truth is that the best purpose for the homeland security advisory system is for the federal bureaucracy to be seen as “doing something,” to prove to the public that politicians and government officials are not asleep at the wheel-if something actually does happen, they can claim they gave fair warning.

But it’s of little use to state and local government officials, as well as the general public, because no clearly defined actions are associated with any of the alert levels.

Throughout all the various warnings — including increasing the alert level from yellow to orange and back to yellow again — the public has been told to go about their normal, everyday lives. Indeed, despite the latest warning of potential attacks against passenger trains, an administration spokesperson urged Americans to “continue to ride our nation’s rails.”

Ultimately, the homeland security advisory system is pointless and useless. And if it’s any indication of how the proposed cabinet-level Office of Homeland Security will work, Americans have every reason to be concerned that the federal government will be able to do little to prevent another 9/11.