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. Last Updated: 07/27/2016

U.S., Britain Tighten Security After Attacks

KENNEBUNKPORT, Maine -- The chaos caused by a series of terrorist strikes in Britain has raised fears that car bomb attacks like those in Iraq have reached Europe, and U.S. airports are tightening security in response.

Late Saturday, Britain raised its security alert level to critical -- the highest possible level, indicating terrorist attacks may be imminent.

Prime Minister Gordon Brown said in a nationally televised interview that Britons must realize that the terrorist threat they face was "long-term and sustained."

Brown urged Britons to remain constantly vigilant. "Everything is being done in our power ... to protect people's lives," he told the BBC in a television interview.

"This weekend's bomb attacks signal a major escalation in the war being waged on us by Islamic terrorists," said Lord Stevens, Brown's terrorism adviser.

"Now al-Qaida has imported the tactics of Baghdad and Bali to the streets of the U.K.," he said in a column in Sunday's News of the World newspaper.

The United States, however, is not raising its terror alert status, President George W. Bush's spokesman and the Homeland Security secretary said Saturday. "There is no indication of any specific or credible threat to the United States -- no change in the overall security level," Tony Snow told reporters in Maine.

Snow said the British government had notified the White House in advance of raising its security level, and that the move did not lead to any change in the threat assessment in the United States.

"We constantly monitor and assess the situation, and adjust our posture as necessary," Snow said.

Still, U.S. officials were wary. Acting out of "an abundance of caution" ahead of the Independence Day holiday on July 4, Homeland Security chief Michael Chertoff said the government was putting in place plans to increase security at airports, on mass transit and at transportation facilities.

"Some of these measures will be visible; others will not," he said in a statement.

"We have no plans at this time to change the national threat level, although we remind everyone the aviation threat level has been raised to orange since last fall," Chertoff said.

Orange is the second highest of five levels on the U.S. terror alert chart and indicates a high risk of terrorist attacks.

The Transportation Security Administration is posting more agents outside terminals at some airports, Snow said.

"There will be some inconvenience of passengers in terms of longer wait times," Snow said. Local police also may take separate measures, he added.

Bush, who spent the day biking and fishing, was kept abreast of the developments in Britain, Snow said. U.S. officials were in contact with their counterparts in Europe, he said.

FBI spokesman Richard Kolko said the bureau stood ready to help British authorities.