Officials step up the patrols and escorts--and try to avoid causing substantial trade delays

The doughty Coast Guard is patrolling the ports at near-World War II levels. Cutters escort cruise ships and high-risk vessels. “Sea marshals” ride shotgun for harbor pilots.

The Customs Service has bought about 4,000 radiation detection wands. For the first time, a handful of customs agents are stationed abroad to spot suspicious ships and cargoes.

At the Port of Los Angeles and Long Beach, divers randomly inspect ship hulls, tankers travel only by daylight and port police give extra protection to high-risk vessels.

“We take command of the engine room,” said Noel Cunningham, chief of the Port of Los Angeles Police. His officers inspect crews’ credentials and “walk the halls of the ship” looking for trouble.

Altogether, the U.S. has about 350 deepwater ports, most lined with chemical plants and other facilities that could multiply the destructive force of a terrorist bomb. More than 2 billion tons of cargo, including 156 million tons of hazardous materials, sailed in and out last year.

A watertight national system for preventing terrorists from planting a bomb among these 2 billion tons of cargo seems years away at best.

One question is how to substantially tighten security without unbearable delays. About 95% of U.S. imports arrive by sea; even modest slowdowns would damage the economy, as steps taken after Sept. 11 almost did.

“Our adversaries used our open system to wage war on us at home,” says Stephen E. Flynn, a former Coast Guard official and senior fellow at the Council on Foreign Relations. “And we reacted by blockading our own economy.”