Oct. 7, 2005 -- A source for information that has led to the terrorism scare on New York City's subways has identified at least one of the attackers by name and claims that the man already is in the United States, ABC News has learned.
The New York Police Department and the FBI have no proof that the person named actually is in the country, or that the person named actually exists. In addition, the Department of Homeland Security emphasized that there is no indication that the person is in the United States.
Still, the NYPD and FBI are investigating allegations that 19 operatives have been deployed to the city to place bombs in the subway, perhaps in briefcases or baby strollers.
Heightened security was visible in New York subway stations today, as police checked bags and kept alert for suspicious behavior. In one incident, authorities briefly closed part of Penn Station, one of the hubs of the city's transit system, to investigate a discarded soda bottle filled with an unidentified green liquid.
In Philadelphia, authorities detained a man wearing camouflage and carrying a backpack at a transit station after he was flagged by bomb-sniffing dogs and they were unsatisfied with his answers to questions.
'Can't Stop Us'
The source of the threat information, arrested in Iraq, passed a polygraph test on the key points regarding the plots against the subway system, ABC News has learned -- though there were indications of deception on other parts of the test.
Based on different interpretations of the polygraph, Navy and CIA intelligence discounted the information. But other agencies analyzing the data felt the inconsistencies only lent credence to the points where the source was telling the truth.
In addition, ABC News has learned, one of two Iraqi insurgents who were sources for the threat information said when arrested, reportedly in perfect English: "You f---ing can't stop us now; it's too late."
A third man escaped arrest.
Sources say the informant told officials that the members of the attack team are made up of five nationalities -- including Afghans, Syrians and Iraqis.
Though the FBI and New York Police Department have portrayed the threat information as "credible," the Department of Homeland Security has downplayed the threat.
Former U.S. counterterrorism czar Richard Clarke, now an ABC News consultant, told "Good Morning America" that the officials may be sending different messages because of jealousy.
"Based upon what we've been told, it's a credible threat, but it's not corroborated," Clarke said. "What does that mean? It means these people are terrorists, but we have only the one source.
"What I would have recommended to the president is we do exactly what the mayor is doing," Clarke added. The Homeland Security sources are "probably upset because they're left out of this. This is an FBI, New York operation."
New York Mayor Michael Bloomberg acknowledged the differences of opinion Friday, saying intelligence often prompts different interpretations, but that as a local official he could not afford to dismiss the information.
"If I'm going to make a mistake, it's going to be on the side of protecting New York City," said Bloomberg, who earlier had vowed, "We will spare no resource. We will spare no expense."
President Bush suggested it was New York's prerogative to act or to inform the public.
"Our job is to gather intelligence and pass it on to local authorities, and they make the judgements necessary to respond," Bush said.
Information on the alleged plot developed when an informant for the Defense Intelligence Agency led a team of military, intelligence and law enforcement in Iraq to three men dubbed "the pharmacists." The informant had been reliable in the past and in this instance was deemed credible because of an ongoing involvement with the three men.
The alleged plot convinced authorities they should rapidly and massively step up security and intelligence measures at New York subway station "feeder stops" in communities where there are large populations in which an attack team could blend in and board the subway with bombs in large briefcases and baby strollers.
The informant gave specific details about the wiring of the bombs, the size of the brief cases, the ethnic identities of the attackers and the name of the alleged attacker purported to be in the United States.
Until Thursday morning, the trio of "pharmacists" was kept under surveillance in the hope that they would lead authorities to the wanted al Qaeda figure in Iraq, Abu Musab al-Zarqawi.
In the meantime, the military gave shoot-to-kill orders in case the trio headed for the Syrian border, the route the informant said they would take out of the country, ABC News has learned.
The three suspects were called "pharmacists" not because of any actual degree in that subject, but because they knew how to mix homemade chemicals that would be turned into high-explosive devices similar to those used in London.
Back to Subways
After several days of work, sources said Thursday, the NYPD became increasingly concerned because it was unable to discredit the initial source and additional information.
NYPD Commissioner Ray Kelly said officers will continue to check bags, briefcases, luggage and strollers, and additional uniformed and undercover officers will be riding in individual subway cars.
Some New Yorkers returning to the subway today were blasé about the threat.
"You can't worry about it," one rider told ABC News' "Good Morning America." "Que sera sera."
But another man expressed some worry to ABC News Radio.
"I really never take the train; this is my first time," he said. "So I am kind of scared. So I am concerned, very concerned."
ABC News' Michael S. James contributed to this report.