The sewage barge and trash boats had finished their work. Refueling proceeded apace. Soon, the USS Cole's routine stop at the Port of Aden would be complete, and her crew back out on patrol.

Then, without warning, the 8,000-plus ton missile destroyer lifted out of the sea. "Instantly I knew that we had been attacked," recalled the ship's commander, Kirk Lippold, in his book, "Front Burner: Al Qaeda's Attack on the USS Cole." From the angle at which the ship was thrown, he knew that something had detonated on the seaward side of the Cole.

A small craft laden with explosives had entered the port and sailed right to its target. Now, 17 sailors lay dead. It was a tragic lesson: Small boats can create big problems.

And small boats are everywhere. America has more to worry about than the safety of ships of battle cruising into foreign ports of call. U.S. waters are becoming more dangerous as well. As U.S. land borders have become less porous for drug and human traffickers, the bad guys have shifted to the seas. More and more, they are using small boats to deliver their loads to American shores.

The shift started as far back as 2007. Even as the border patrol was successfully cracking down on the busiest smuggling routes on the Mexican border, authorities in San Diego were receiving more and more reports of small craft without running lights racing in the dark to lonely stretches of southern California's beaches or dumping their passengers at small, sleepy marinas.

It didn't take long to figure out these runs were no joy rides. They were business trips -- cartel business.

Today, America is being invaded by "Pangas" -- modest-sized, open, outboard-powered boats that are common fixture throughout Latin American ports. A typical small craft comes packed with a load of 1,500 to 4,000 pounds of marijuana and a platoon of illegal immigrants. Many of those looking to enter the United States unlawfully aren't looking for regular work. Often, they are gang-bangers, offenders with active warrants or criminal records who wouldn't even think of trying to slip through a land border crossing unnoticed.

Small boat smuggling is a big problem in part because it is easy to hide the wolves among the sheep. There are more than 500,000 small, recreational craft registered in the southern California area alone.

Cartel operations are dangerous for everyone involved -- from the passengers being smuggled, to the police, border patrol officials and U.S. Coast Guard crews trying to catch them. In fact, migrants trying to walk across open desert may be at less risk than those braving a voyage on the open seas to reach an unguarded piece of American coast line.

The U.S. Coast Guard and Customs and Border Protection as well as state and local law enforcement lack the assets and technology to keep up with the threat. And the bad guys have figured this out. Increasingly, they are bumping marijuana to make room for more high-value cargo like cocaine and migrants from Asia.

While the danger is going up, the Department of Homeland Security's capacity is not.

Many of the vessels that support Coast Guard missions have already exceeded their expected service lives. In many cases, maintenance and repair are not enough to keep these ships operational. Resources aren't keeping up with requirements -- and that doesn't even account for what the service really needs to effectively deal with the Panga invasion.

It is debatable whether border security is getting better or the threat is just shifting from land to sea. The deteriorating state of our maritime security raises troubling new questions.

-Examiner Columnist James Jay Carafano is vice president for Defense and Foreign Policy Studies at the Heritage Foundation.