GREEN BAY, Wis. — President Bush said yesterday that a plot to blow up multiple flights between Britain and America shows “this nation is at war with Islamic fascists.”

“This country is safer than it was prior to 9/11,” Mr. Bush said from the airport tarmac here, where he was appearing at events focused on the economy. “We’ve taken a lot of measures to protect the American people, but obviously we’re not completely safe. … It is a mistake to believe there is no threat to the United States of America.”

The president laid the blame for the foiled attack squarely on Al Qaeda-type terrorism. “This nation is at war with Islamic fascists who will use any means to destroy those of us who love freedom, to hurt our nation,” he said, his remarks carried live on television.

Mr. Bush urged Americans to be patient with the many inconveniences to result from the increased threat level that the plot prompted him to approve.

While on vacation in Crawford, Texas, Mr. Bush has been fully informed of the investigations that led to the arrest of 24 people in Britain who are accused of being involved in the plan, which officials said involved explosives smuggled onboard flights in hand luggage.

The White House press secretary, Tony Snow, said Mr. Bush on Wednesday approved raising the threat level to red for all flights from Britain, designating a severe risk of terrorist attacks. The secretary of homeland security, Michael Chertoff, and the Homeland Security Council also recommended that all other flights be put under an orange alert, one step below the highest level, and Mr. Bush approved that as well.

“We do believe the plot involved flights from the U.K. to the U.S.and was a direct threat to the United States,” Mr. Snow said.

The increased security as a result of the new threat level is a necessary inconvenience, he said.

“You can’t go overboard when you’re trying to save lives,” Mr. Snow said, speaking to reporters traveling with Mr. Bush on Air Force One en route to Wisconsin. Still, despite what he called the serious nature of the threat, Mr. Snow said: “It is safe to travel.”

Because Mr. Bush had been getting regular briefings on the developments for days, Mr. Snow said Mr. Bush was not awakened overnight as action by British authorities was made public.

He and Prime Minister Blair held a lengthy teleconference on the matter Sunday and spoke again Wednesday by phone, Mr. Snow said.

“There were some signs,” Mr. Snow said. “They thought it was time to move,” he said of British authorities.

After the remarks on the plot, Mr. Bush was keeping to his plans to highlight the economy and attend a GOP fund-raiser.