WASHINGTON — For people who have grown anxious about U.S. port security because a Dubai company may soon manage operations at six container terminals on the East Coast, Kim Petersen suggests that the real grounds for concern lie elsewhere — such as the fence he saw at a West African port a few months ago.

The newly built fence was a source of pride to the port's officials, who wanted to show that they were protecting their facility against any terrorists seeking to sneak a bomb aboard a U.S.-bound container. But it was a 5 1/2-foot-tall chain-link fence — hardly sufficient for the task, said Petersen, president of SeaSecure, a maritime security firm in Fort Lauderdale, Fla.

The story illustrates a point emphasized by many people familiar with security operations at U.S. ports: Among all the reasons to fret about vulnerabilities to terrorist attacks, the nationality of the companies managing the terminals is one of the least worrisome.

"There are many, many problems that we face in maritime security — and they're not the United Arab Emirates," Petersen said, referring to the Persian Gulf nation of which Dubai is a part.

Nonetheless, politicians from both parties continue to pelt the Bush administration with criticism for its decision to allow Dubai Ports World, a fast-growing business owned by the Dubai government, to buy Peninsular and Oriental Steam Navigation Co., a British maritime firm that manages terminals in Baltimore, New Jersey, New Orleans and several other major ports. At a Senate Armed Services Committee hearing yesterday, lawmakers acknowledged that the UAE has become an important U.S. ally in the Persian Gulf region, but repeatedly cited the UAE's role in recognizing the Taliban before the Sept. 11, 2001, terrorist attacks, and the lax supervision of its banking system that allowed some of the hijackers to finance their plans.

But such arguments bypass some crucial questions: What do the companies managing U.S. terminals — most of which are owned by Asian and European shipping giants — do that is so important to protecting against terrorist attacks? And how much difference would it make if Dubai Ports World joined their ranks?

Administration officials have said in recent days that security at U.S. ports is the responsibility of the Coast Guard and U.S. Customs and Border Protection, with the terminal operators responsible for little more than transferring containers from ships to railroad cars and trucks.

That overstates the role government agencies play.

"They've been saying that Customs and the Coast Guard are in charge of security; yes, they're in charge, but they're not usually present," said Carl Bentzel, a former congressional aide who helped write the 2002 act regulating port security.

The private terminal operators are almost always responsible for guarding the area around their facilities, although they must submit their security plans to the Coast Guard, which monitors and inspects them. In some cases, the companies X-ray incoming containers to see whether the contents appear to match the manifest, although Customs agents are solely responsible for "intrusive" inspections — that is, opening containers and examining the cargo.

That procedure is performed on about 5 percent of containers entering the United States.

The security personnel employed by the terminal companies vary from port to port, but according to several companies, the guards are often supplied by local private security firms.

"The lowest-paying jobs on the waterfront are security people," said Stephen Flynn, a ports expert at the Council on Foreign Relations. "But is that a problem for foreign ownership? No. It's a problem for everybody."

Shifting ownership from Britain's P&O to Dubai Ports World would not affect those arrangements at the terminals in question, company officials said. Consider, for example, the situation at the Philadelphia port, where Dubai Ports World would obtain 50 percent control over a local outfit that runs one terminal out of eight leased from the Philadelphia Regional Port Authority.

Robert Palaima, who runs the local company, said yesterday that he hires guards from a union that provides security officers and police guards under a security plan approved by the Coast Guard, which carried out a full-day inspection this week.

Cargo loading and unloading is done by work gangs supplied by the International Longshoremen's Association, which Palaima described as "the most patriotic of unions."

And there would be no changes in the work force even if the Dubai Ports World takeover goes through, he said, adding: "I am sick and tired of all this uproar. We're patriots and nothing will change."

Much more serious, in the view of Petersen and other experts, are gaps in security that have nothing to do with the Dubai takeover.

"We've spent barely $700 million in federal grants to U.S. ports for security, compared with almost $20 billion for aviation security," Petersen said. "And most important, we are doing an abysmal job in assisting ports in the developing world in improving security to even minimal acceptable standards."