It's late on a Thursday night, and a nondescript, low-riding, 32-foot workboat chugs quietly into one of the nation's largest seaports and heads for a pier near a cluster of oil storage tanks. In the small wheelhouse are three men – the skipper, a deckhand and an explosives expert – on a clandestine suicide mission.

Seconds after the vessel ties up, the crew detonates its hidden cargo – a diesel-fuel bomb with plastic explosives – turning the shoreside oil tanks into an inferno and giving the city its first taste of maritime terrorism. The port is shut for days, and shipping near other major U.S. harbors slows to a crawl.Staff Sgt. Dominic HauserPetty Officer 3rd Class Jason Miele, Yorktown, Va., defends the USS Yorktown docked on the Ashley River during exercise Harbor Shield 2002 held in Charleston S.C. on Apr. 17, 2002.

No such attack has yet been launched against a U.S. port or waterfront target, but the Department of Homeland Security, the U.S. Coast Guard and other key federal and state law enforcement agencies are focusing on the small-boat security threat as a serious gap in the nation's defense against terrorist attacks.

"There is no intelligence right now that there's a credible risk" of this kind of attack, says Admiral Thad Allen, commandant of the Coast Guard. "But the vulnerability is there."

While the government has taken steps to tighten security for large passenger and cargo vessels (those with displacements of 300 gross tons or more), it has done little to meet the threat of terrorists using small craft – either fishing vessels or recreational boats – to carry explosives or even weapons of mass destruction.

Moreover, U.S. authorities may be hamstrung to do much for several more years.

An effort by Allen last June to sound out small-boat operators on a variety of ideas for tightening security for recreational boats and small commercial vessels drew an immediate backlash from all quarters – and ended with little beyond an agreement by boating interest groups to think about the problem further.

"What I'm trying to do is to kind of stick my toe in the water and see if I get bit by a piranha," the admiral told a group of state legislators before the National Small Vessel Security Summit, at which authorities unveiled a spate of possible steps to help identify operators and passengers of such boats.

He didn't have to wait long for a reaction. "These are ill-conceived solutions that will inconvenience everyone and not result in a substantial increase in security," Michael G. Sciulla, senior vice-president of the BoatU.S. (the Boat Owners Association of the United States), said following Allen's remarks. Other industry interest groups had similar responses. Chastened, the Coast Guard set up working groups with industry leaders to mull the problem further.

It doesn't take much to appreciate the potential of the small-boat threat. Authorities cite the October 2000 attack on the USS Cole, in which terrorists in the Yemini port of Aden used a small boat to approach the port side of the destroyer and set off an explosion that blew a large hole in the warship's hull. It killed 17 U.S. sailors and injured 39 more.

In August 2005, terrorists fired rocket-propelled grenades at two U.S. warships moored in Aqaba, Jordan. And in November of that year, pirates attacked a cruise liner 100 miles off the coast of Somalia, using two 25-foot rigid inflatable boats.

"This is not merely the question of a theoretical threat, but it's the question of a threat that has already come to pass," Homeland Security Secretary Michael Chertoff said Monday, addressing several hundred members of the boating industry at an event sponsored by the National Marine Manufacturers Association. "And we have to, therefore, accept the reality that there is a risk to our security that comes from someone misusing a boat for terrorist purposes."

BUY, RENT OR COMMANDEER

Small recreational boats and commercial vessels are easy to buy or rent – or even commandeer – in the United States. There are more than 20 million pleasure craft, 82,000 fishing vessels and 100,000 other small commercial vessels in the U.S. Unlike private aircraft, most of them don't require a license to operate. They can be used as delivery vehicles or as platforms for launching missiles or grenades. And many have interior spaces large enough to smuggle in large amounts of explosives or even nuclear or radiological bombs.US Air Force Staff Sgt. Dominic HauserCoast Guard members receive briefing prior to boat interception procedures during exercise Harbor Shield, an anti-terrorism exercise in Charleston, S.C.

"We know that small boats can essentially become vehicles for bombs," says Stephen Flynn, a former Coast Guard officer who's now a homeland security scholar at the New York-based Council on Foreign Relations. "You can get these boats anywhere, and they are virtually unpoliced."

The Coast Guard shares that concern. "We've gotten a lot better on [tracking] big ships, but there's one remaining gap – the large volume of smaller vessels, which do not have anywhere near the same degree of visibility," says Rear Admiral Brian Salerno, assistant commandant of the Coast Guard for boating safety, security and seamanship, who is overseeing the small boat security effort. "It's an issue that people are concerned about."

On Monday, Chertoff spoke in terms of balancing government action with boaters' needs in order to mitigate risks. "The only way to really guarantee the risk could never come to pass would be to ban the activity outright, which I hasten to add we have no intention of doing," he said, adding that, "We try not to eliminate the risk but to manage the risk, to reduce the risk to a reasonable level at a reasonable cost, recognizing that that's not an insurance against anything ever happening."

To be sure, the government hasn't simply stood still on small-boat security. The Coast Guard has stepped up its boardings of small craft, and is intensifying its intelligence-gathering on such vessels and at marinas and other shore facilities. It's also providing armed escorts for liquefied natural gas (LNG) tankers and other potential targets. It has set up restricted zones in high-risk areas. And DHS is requiring persons who work on commercial vessels or in shoreside port facilities to obtain federal identification credentials.

The service has begun activating its new Rescue 21 satellite-linked vessel-positioning and communications system. While Rescue 21 is designed primarily to enhance search-and-rescue operations, officials say it also will help keep tabs on potential terrorists by making it easier to spot and track small boats.

Finally, the Coast Guard has launched an America's Waterways Watch program – similar to the Neighborhood Watch effort that has long been in place in shoreside communities – to enlist boaters' aid in identifying suspicious happenings on rivers, bays and other bodies of water and reporting them to homeland security officials.

But AWW, as it's called, is still largely a public relations effort, and high-tech vessel identification schemes – such as requiring vessel owners to obtain licenses and photo-identification cards, or mandating that small boats carry transponders, as airplanes must do to identify themselves – don't seem likely to gain acceptance anytime soon.

TOO COSTLY AND INTRUSIVE?

Boating industry groups protest that such measures would violate boaters' privacy, that the equipment they would require would cost too much, and, in the long run, that they would not accomplish much in identifying and tracking would-be maritime terrorists. Some boaters view their right to operate their boats without regulation much as gun-enthusiasts regard the Second Amendment.

Ironically, one problem that homeland security officials face in drumming up support for more protection is that, at least so far, there's been little to demonstrate the seriousness of the small-vessel threat the way the Twin Towers attack did in case of the global war on terrorism. Like the USS Cole incident, all the maritime examples have occurred in other countries.Air Force Staff Sgt. Dominic HauserPetty Officer 2nd Class Corey Chiermonte, Petty Officer 3rd Class Jason Miele, Yorktown, Va., and Petty Officer 1st Class Scott Pardington, Camp Lejeune, N.C., defend the USS Yorktown docked on the Ashley River.

There have been almost daily reports of what authorities call "anomalies" – suspicious-looking people taking photos of bridges, ferry boats and even engineering spaces and loading procedures for big ships – but so far they haven't resulted in any terrorist incidents.

"And we would like to keep it that way," Salerno says.

Where the small-boat security effort will go next still is uncertain. On Monday, Chertoff issued a new "small-vessel security strategy" document that lays out broad goals for coping with the threat and calls for enhanced government-industry cooperation to coordinate efforts to gather data on small vessels and track those that seem suspicious. But it didn't contain any specifics.

The Department of Homeland Security has conducted regional government-industry meetings on small-vessel security in Cleveland, Orlando, and Long Beach, Calif., and is slated to hold one in Buzzard's Bay, Mass., in June, but authorities say they aren't likely to result in any new regulations.

The Council on Foreign Relations' Stephen Flynn says the Coast Guard might be able to nab more suspected small-boat terrorists if it stopped treating intelligence about them as classified material and instead began disseminating substantially more information to the public, much as authorities did during World War II when they wanted citizens to help find and expose saboteurs. Today, only law enforcement officers who have proper security clearances can gain access to such material.

"What they're doing now is the wrong approach," Flynn says. "There never will be enough Coast Guard personnel to keep tabs on these cases, and the information now being provided to the public about what we're worried about and what we're doing about it is practically useless. They should be assuming that people would be patriots, and engaging them in the effort."

It's difficult to tell whether the Coast Guard will take up that suggestion anytime soon, but for now one thing is clear: Talk about licensing recreational boaters, requiring them to obtain photo-identification cards or requiring them to carry high-tech transponders to help track their vessels is dead in the water.

"If there's going to be any requirement for tracking [systems], it's likely to have very limited application – say, only for commercial vessels, and even then at the larger end," says the Coast Guard's Salerno.

Meanwhile, the Coast Guard and the industry are pondering some beginning steps. Among them are the possible creation of national boat registry that can be used by federal, state and local law enforcement agencies; research into less expensive transponder technology and a more effective procedure for reporting suspect terrorist activities.

"The dialogue is ongoing," Salerno says.

Art Pine is a veteran journalist who has served as a Washington correspondent for the Baltimore Sun, The Washington Post, The Wall Street Journal, and the Los Angeles Times. He is a longtime Chesapeake Bay sailor and a Coast Guard-licensed captain.