The chairman and ranking Democrat on the House Homeland Security Committee (search) are calling for the rapid closing of any gaps in U.S. terrorism defenses, highlighting the need for action on many fronts, not just international air routes.

Committee chairman Christopher Cox (search), R-Calif., said the government is working on an assessment of vulnerabilities. "We're doing everything we can to speed that along, to hasten it, but we've got to prioritize," he said Sunday in a televised interview.

Appearing with Cox, Rep. Jane Harman (search), D-Calif., said: "The ports of L.A. and Long Beach are where 43 percent of the container traffic for America enters and exits, and yet we still don't have a good system of inspecting" cargo.

Extra security checks again delayed a British Airways flight to Washington Dulles International Airport on Sunday and the United States entered a third consecutive week on a high state of alert for terrorists.

Fourteen flights on British Airways, Aeromexico and Air France have been canceled or delayed since New Year's Eve because of security fears. Air France canceled six flights between Paris and Los Angeles on Christmas Eve and Christmas Day.

The U.S. government raised the national threat level on Dec. 21 to orange, indicating a high risk of terrorist attack, and said threat indicators are perhaps greater now than at any point since Sept. 11, 2001 (search). Dulles International, point of origin for the Sept. 11 flight that terrorist hijackers crashed into the Pentagon, was the destination or takeoff point for eight of the canceled or delayed flights since Wednesday.

British Transport Secretary Alistair Darling said "I fear that for many years to come we are going to be living in an age where there is going to be a heightened state of alert.

"Sometimes it will be quite severe, at other times perhaps less so," Darling told the British Broadcasting Corp. program "Breakfast with Frost."

Darling said the decision to cancel the flights was justified on the basis of intelligence warnings.

"We are going to have to get used to increased security at airports. From time to time that will be noticeable, and at other times maybe things will be going on behind the scenes," Darling said.