MCLEAN, Va.— President Bush said the unraveling of a plot to blow up airliners flying out of London demonstrates that America faces a years-long battle against terrorism.

“America is safer than it has been, yet it is not yet safe,” Mr. Bush said yesterday after a series of briefings at the National Counterterrorism Center in McLean, Va. The work at the center is “indicative of the challenge we face not only this week, but this year and the years to come.”

The American public is refocused on the threat of terrorism following the arrests in Britain of 24 people suspected of plotting to smuggle liquid explosives aboard American-bound airliners. Another suspect in the case was arrested yesterday. Passengers in America and Britain are undergoing more stringent security checks, and delays caused by screening prompted British airlines to cancel some flights for the sixth day.

The counterterrorism center that Mr. Bush visited yesterday is the primary facility for integrating and analyzing intelligence about terrorism and includes personnel from the CIA, the Federal Bureau of Investigation, and the Departments of State, Defense, and Homeland Security.

The president lauded the officials and analysts for their work and for their cooperation with agencies overseas.

“Recently, we saw the fruits of their labor in conjunction with their counterparts in Britain,” Mr. Bush said. “Our solemn duty in the federal government is to protect the American people. I will assure the American people we’re doing everything in our power to protect them.”

Among those participating in the meetings with Mr. Bush are Defense Secretary Rumsfeld, Secretary of State Rice, Attorney General Alberto Gonzales and the director of central intelligence, Michael Hayden.

Homeland Security Secretary Michael Chertoff, who also is participating in the meetings yesterday, said this week that the investigation into the Britain plot isn’t finished and that authorities are concerned that other terrorist groups might “think we are distracted” and try to take advantage.

The Britain plot involved using liquid explosives disguised as drinks and other seemingly benign objects. The Transportation Security Administration is prohibiting passengers from bringing liquids or gels aboard planes in carry-on luggage. Exceptions are made for small amounts of medications or food for infants.

An August 11–13 CBS News poll found that terrorism jumped to the second biggest concern of American adults from a survey taken last month. Iraq remains the top concern, cited by 28% of those polled. Seventeen percent cited terrorism, up from 7% who cited it in July. That moved terrorism ahead of the economy and fuel prices.

As part of a series of annual meetings, Mr. Bush spent Monday at the Pentagon and State Department to discuss Lebanon, Iraq, Iran, and other issues. On Friday, he will meet with his economic advisers at Camp David, where he will spend the weekend.