Security level was sharply increased in and around New York City's subways on Thursday after city officials said they were notified by federal authorities in Washington of a terrorist threat that for the first time specifically named the city's transit system.
The measures were announced by Mayor Michael R. Bloomberg, along with Police Commissioner Raymond W. Kelly and the head of the New York F.B.I. office, Mark J. Mershon, after an American military operation with the C.I.A. and the F.B.I. in Iraq yesterday and Wednesday, according to law enforcement officials. The operation, the officials said, was aimed at disrupting the threat.
Some officials in Washington, in interviews last night, played down the nature of the threat. While not entirely dismissing it, a spokesman for the Department of Homeland Security described it as "specific yet noncredible," adding that the intelligence community had concluded that the information was of "doubtful credibility."
Several law enforcement officials said an investigation had yet to corroborate any of the details.
The officials, who spoke on the condition of anonymity, said the operation in Iraq resulted in two people being taken into custody. They said a third was being sought.
Information about the threat, the officials said, came to light last weekend from an intelligence source who told federal authorities that the three men in Iraq had planned to meet with other operatives in New York, reports the New York Times.
Kelly asked the public to report anything suspicious and try to refrain from bringing bags and packages into the subway system. New York's subway system, the largest in the U.S., carries 4.5 million passengers on an average weekday, according to the Metropolitan Transportation Authority Web site.
New York police and FBI agents continue to investigate the threat, Kelly said. Bloomberg said authorities have no reason to believe that anyone intending an imminent attack is in New York now.
Mark Mershon, special agent in charge of the FBI's New York City field office, said "classified operations have partially disrupted this threat."
"There are ongoing investigative and enforcement activities and there's the possibility that this particular case will be resolved in the coming days," Mershon said.
Some officials played down the urgency of the threat. In Washington, Homeland Security Department spokesman Brian Doyle said "there is doubtful credibility to this source." Senator Charles Schumer, a New York Democrat, characterized the threat as "specific but not corroborated and not of the highest credibility," informs Bloomberg.