New York officials scaled back security in the city's subways yesterday after federal and local law enforcement authorities discounted the report of a terrorist threat to the city's underground transportation system.
Mayor Michael R. Bloomberg said that the extraordinary measures put in place on Thursday - police officers on every train, major shows of force at transportation centers - would be relaxed, but that the city would continue many of the enhanced measures it has taken to protect the subways since the bombings in London in July.
"There was no there there," one senior United States counterterrorism official said of the possible threat that surfaced publicly late last week.
From the outset, some federal officials, including those with the Department of Homeland Security, questioned just how real a plot against the subway system had been, and while some supported the city's measures, at least one official said he was astonished by how the city had reacted.
But Mr. Bloomberg and other city officials were adamant yesterday that they had made the right decision, to go public with the report and heighten security. New York officials described the threat last week as alarming for its specificity and timing, noting that information on the possible plot was strong enough to prompt a military operation that swept up three Iraqi men thought to be involved.
City officials also reiterated yesterday that they would much rather risk frightening and inconveniencing New Yorkers than be caught unprepared for an attack.
Law enforcement officials, speaking on the condition of anonymity because the information in the case is classified, said that an American investigation, conducted largely in Iraq, has yielded no evidence that a plot was in motion or being actively contemplated. The outlines of the alleged plot, based on the word of an informant, were that Al Qaeda operatives in Iraq were coordinating with others, some perhaps already in New York, to hide bombs in baby strollers, packages and briefcases and blow them up in subways.
But the officials said that after taking the three men into custody last week in Iraq, they found no fake passports, no travel documents, no viable travel route from Iraq to New York, and no apparent contact or telephone calls from those in Iraq to people in New York. In addition, the officials said that two of the men detained in Iraq had been given polygraph tests that indicated they were not part of any plot.
At a minimum, then, the case of the subway bomb plot appears to be the latest addition to the country's post-9/11 struggle to meet the sometimes conflicting demands of gathering good intelligence, preventing harm and informing and reassuring the public along the way. It is an effort that has regularly proved awkward and even contradictory, as federal and local agencies make their own assessments and meet their own specific obligations.
The F.B.I.'s chief spokesman, John Miller, an assistant director, said yesterday that the agency supported the city's actions. "Since 9/11, one of the toughest balances has been to pass on all threat information quickly while understanding you have to vet it later, especially when you have to give it to a local government that could be affected," he said in a telephone interview from Washington. "We've also encouraged local governments to take whatever steps they think are prudent until the information is vetted. In this case, everybody did what they were supposed to do."
Mark J. Mershon, the head of the New York F.B.I. office, said in a statement last night that it was the agency's policy to pass on threat information immediately to any potentially threatened city. "While some evaluation continues, we are comfortable that the steps taken overseas have neutralized any threat that may or may not have existed," he said.
Officials at the Department of Homeland Security, who had raised doubts about the credibility of the threat and had seemed to suggest that the city was overreacting, said little yesterday. A department spokesman, Russ Knocke, said only, "No information has been uncovered to enable the intelligence community to substantiate the threat information."
Asked yesterday about the threat, Mr. Bloomberg said that federal authorities had told the city they were unable to verify it. He said that since the period of the strike was passing, security would be rolled back. But he noted that the city remained at level orange - a higher state of alert than the rest of the country.
"We're going to take every single threat that has any chance of being credible seriously, and do exactly what we did," he said.
Fernando Ferrer, Mr. Bloomberg's Democratic challenger in the race for mayor, issued a statement yesterday saying that the mayor should disclose what, and when, he knew about the threat, and precisely why he acted as he did. Edward Skyler, a spokesman for Mr. Bloomberg, said that during such an extensive investigation, "the mayor doesn't have the luxury of knowing whether the threat will ultimately be determined to be credible or not."
More details emerged about the alleged threat and the investigation into it. One law enforcement official, who spoke on the condition of anonymity because much about the case is classified, said that the three men continue to be interrogated in Iraq.
The source who provided the information, the official said, had been mostly accurate when he gave information to his Defense Intelligence Agency handlers about actions inside Iraq and largely wrong about actions elsewhere.
"The process is not a clean one here," the official said. "Ever."