NYC Scales Back Subway Security

After four days on high alert, New York City police announced Monday that they were scaling back a subway security crackdown prompted by a report of an al Qaeda plot to blow up trains.

City officials said they were still investigating claims by an informant that al Qaeda operatives in Iraq had hatched a plot to attack the subways using baby strollers packed with remote-controlled explosives. They continued to defend a decision to flood the subways last Thursday with thousands of extra police officers, despite doubts by U.S. Homeland Security officials the threat was credible.

Mayor Mike Bloomberg said he had no regrets.

"We've got to take every threat seriously and that is what we are going to do," he said Sunday.

Interrogations of suspects captured in Iraq last week after an informant's tip about bomb-laden suitcases and baby carriages have yet to yield evidence that the plot was real, officials said Sunday.

"The intelligence community has been able to determine that there are very serious doubts about the credibility of this specific threat," Homeland Security Department spokesman Russ Knocke said. "This is after ongoing review and analysis."

U.S. Homeland Security officials have been skeptical about the threat since it was publicly announced Thursday, but officials who were more assertive about the potential danger last week also appeared to be softening their assessment.

"I believe in the short term we'll have a much better sense of whether or not this has, you know, real substance to it," Police Commissioner Ray Kelly said on CNN's Late Edition.

A Homeland Security memo said the attack might have been planned to take place on or around Sunday.

Police doubled the number of daily bag checks and sent thousands of extra officers into the transit system, some in plainclothes and many others in uniform.

The informant who prompted the plot investigation has provided a mix of true and false information in past investigations, Kelly said on CNN. Asked whether the informant had passed a polygraph test, he replied, "That source was deemed to be, yes, believing in the information that was put forward."

The commissioner said he remained confident that the city acted properly.

"This threat was very, very specific. It had specific time, specific object and modality. So, you know, we had to do what we did," Kelly said.

The informant, who had spent time in Afghanistan, told U.S. intelligence that a group of men were plotting to attack New York subways with timed or remotely detonated bombs in strollers and bags. U.S. forces in Iraq arrested two plotters Thursday, prompting Bloomberg, Kelly and the FBI's New York office to announce security was being increased in the subways. A third suspect was arrested Friday.