WASHINGTON -- President Bush lowered the nationwide "high risk" terror alert back to code yellow -- "significant risk" -- on Tuesday.

Administration officials credited the arrests of suspected terrorists from Buffalo to Pakistan to Bahrain, while warning that the danger of another attack remains.

U.S. intelligence officials continue to believe that operatives of Osama bin Laden's al-Qaida terror network are at work on American soil, Attorney General John Ashcroft said.

"I want to emphasize that we are not saying there is no risk," Ashcroft said. "We consider the risk to still be an elevated risk. It's a very serious risk. And we ask for citizens to remain alert."

On the unanimous recommendation of his homeland security council, Bush returned the national threat level to "elevated" -- in the middle of the government's color-coded scale -- two weeks after kicking it up a notch to the orange, high-risk status in time for the anniversary of the Sept. 11 attacks.

Arrests ease tension

Ashcroft and Homeland Security Director Tom Ridge, two of the officials contributing to the recommendation to Bush, cited recent arrests of suspected members of al-Qaida in Buffalo, N.Y., Singapore, Yemen, Bahrain and Pakistan.

"These actions have disrupted terrorist operations by neutralizing certain senior al-Qaida leadership and removing other terrorist planners and operatives," Ashcroft and Ridge said in a joint statement announcing Bush's decision.

Ashcroft elaborated at a news conference, saying that information from the intelligence community and the passing of time since the Sept. 11 anniversary also contributed to the status change.

"We have no reason to believe that the United States is absent al-Qaida-associated individuals," he said. "We have not lost sight of the fact that tens of thousands of individuals were trained by al-Qaida."

Tuesday's change came after Bush met with senior administration officials who review daily intelligence, weigh the potential for attack on U.S. targets and prepare threat-level recommendations for the president.

In the days leading up to the Sept. 11 anniversary, intelligence agencies warned the White House that terrorists operating in several South Asian countries and linked to al-Qaida hoped to explode car bombs or launch other attacks on American facilities abroad.