The Coast Guard will board every foreign-flagged vessel that sails into a U.S. port beginning Thursday to check whether it is complying with rules aimed at foiling terrorists.

A maritime treaty signed by about 150 countries requires each ship to have a security officer, alarm system, automatic identification system, access restrictions to the engine room and bridge, and a method of checking IDs of people who board. Each ship must have a certificate signed by the country that flags it saying it is in compliance with the treaty.

Rear Adm. Larry Hereth (search) said that 700 Coast Guardsmen, including about 500 reservists, will be part of the effort to board all ships as they enter the ports.

"We're going to take a pretty hard line," said Hereth, the Coast Guard's director of port security.

The Coast Guard (search) has a range of sanctions that can be imposed on ships that fail to meet the standards, depending on what the problem is, Hereth said. An administrative glitch could be repaired onboard, he said, but if it should appear that the ship's operators have done little to comply the vessel could be turned away.

The Coast Guard also can detain a ship and require it to hire security guards until it has come into compliance. Or the Coast Guard can add points to the ship's risk-assessment score, which would mean that the ship is inspected the next time it calls at a U.S. port, Hereth said.

Joe Cox, president of the Chamber of Shipping of America (search), which represents U.S. ship owners, said he expects the Coast Guard to enforce strictly the requirement that each vessel has a signed certificate saying it complies with the standards.

"I don't think there's a ship around here dumb enough to come into U.S. waters without the certificate," Cox said.

Many foreign-flagged ships and overseas ports won't meet the standards, according to statistics provided by the International Maritime Organization (search), the United Nations agency that monitors shipping safety.

According to the IMO's most recent figures, 71 percent of tankers, 89 percent of cruise ships and 56 percent of cargo ships had certificates. Only 32 percent of port facilities had approved security plans required under the treaty.

Although ships and ports in most of Europe and Japan have complied, maritime facilities in some developing countries remain problematic, the IMO says.

The agency has no enforcement powers, however, and relies instead on the implicit economic threat to governments that don't comply with the new International Ship and Port Facility Security Code (search). For example, ships from countries that don't meet the higher standards might be refused port privileges by nations that have.

Hereth said the Coast Guard would pressure non-U.S. ports to tighten security so they meet the new standards.

Coast Guard spokeswoman Jolie Shifflet said ships sailing into U.S. waters increasingly were reaching the standards. On Tuesday, 78 percent of the 192 foreign-flagged ships calling on U.S. ports were in compliance, up from 65 percent the previous two days.

"We're projecting that to continue to rise," Shifflet said, adding that 142 of the 150 ships that plan to enter U.S. ports on Thursday said they have the certificates.

Thursday also is the deadline for U.S. ports to comply with a maritime security law passed by Congress in November 2002. All but a handful of the thousands of port facilities and vessels will be up to U.S. security standards, Shifflet said.