Washington ? The week before the Sept. 11 terrorist attacks on New York and Washington, the Coast Guard cutter Tahoma was cruising the peaceful waters off New England, protecting codfish and scallops from illegal fishermen.

A week later, the 270-foot vessel was patrolling New York harbor, machine guns ready, warily shepherding foreign ships into port beneath the smoke still streaming from the ruins of the World Trade Center.

The Tahoma’s switched assignment illustrates the dramatic changes taking place in the Coast Guard’s mission.

Along with rescuing boaters in peril, intercepting drug smugglers, breaking ice in polar seas and enforcing safety regulations, the 211-year-old coastal service has become a key player in President Bush’s Homeland Security program.

Port security is now “Job One” for the Coast Guard, Adm. James Loy, the agency’s commandant, told reporters at a briefing on his new, expanded budget Wednesday. A 19 percent jump in the service’s operating expenses, the largest increase since World War II, is designed to reduce the alarming vulnerability of America’s 361 ports and 95,000 miles of rivers, lakes and coastlines.

About 7,500 foreign ships, manned by 200,000 foreign sailors, enter U.S. ports every year. Six million truck-sized cargo containers are unloaded on the docks, but only 2 percent are physically inspected.

Many ports are in or near big cities packed with millions of unprotected civilians.

Fuel tanks, chemical plants and vital bridges line the shores. For suicidal terrorists, a tanker would make an even more powerful “bomb” than a jetliner.

Any of these ships or containers “could be used for mass destruction,” said Capt. Wayne Justice, the Coast Guard’s acting director of resources. “We are uniquely situated to recognize terrorist threats (and) prevent possible catastrophic attack,” he said.

Doubling funds

If Congress approves the Coast Guard budget, federal spending on port and coastal security will double to slightly more than $1 billion in the coming year. It will be the Coast Guard’s highest priority, bypassing such traditional tasks as search-and-rescue operations, marine safety and maintaining aids to navigation.

Loy said protection against terrorism claimed only 2 cents out of every dollar the Coast Guard was spending on Sept. 10. But as of Sept. 12, he said, the share shot up to 50 cents per dollar.

This shift is forcing cutbacks in some of the Coast Guard’s normal duties. Drug enforcement, for example, is down from 18 percent to 13 percent of operating expenses. Marine safety drops from 14 percent to 5 percent.

Fishery protection dips from 15 percent to 11 percent.

“We’ll have to borrow a little from other functions,” Deputy Commandant Tom Collins admitted. “We’ll be able to cover the more critical elements, but not as much as before 9/11. There are still going to be some gaps.”

Since the terrorist attacks, the Coast Guard has begun a three-year expansion program to add 8,000 new military and civilian personnel. That would provide a total force of 50,000 men and women still far fewer than the 230,000 who served during World War II.

In other actions, foreign ships are now required to give four days instead of the previous 24 hours of advance notice when they are approaching American ports. This is to allow more time to check lists of the crew and passengers and inspect the cargo.

Armed “sea marshals” board “high interest vessels” meaning potentially suspicious ships and Coast Guard boats escort them into port.

In the five months since Sept. 11, nearly 2,000 ships have been boarded and inspected, but that’s still barely half of the 20 or so arriving each day. Ships carrying hazardous cargoes such as oil or natural gas and vessels from Middle Eastern ports get priority.

In Miami, New Orleans and elsewhere, armed teams board inbound cruise ships and remain on the bridge and in the engine room until they dock.

To beef up its operations, the U.S. Navy has lent the Coast Guard seven patrol ships, with Navy crews but Coast Guard commanders. Special port security units have been deployed in Boston, New York, Seattle and Los Angeles-Long Beach.