Could the war be moving back to New York City?

A "credible threat" to the subway system has prompted a vast mobilization of police officers, law enforcement sources said today.

Hundreds of officers were expected to be dispatched as early as this afternoon to every station in Manhattan -- and possibly system wide -- to thwart the attack, which was said to timed to the Jewish High Holidays and the start of the Muslim holy month of Ramadan.

UPDATE:

More:

According to sources in intelligence, emergency services and police headquarters, when three Iraqi insurgents were arrested several days ago during a raid by a joint FBI-CIA team, one of those caught disclosed the threat. Because it slipped out during the arrest, the plot was deemed credible.

After several days of work, sources said, the NYPD is increasingly concerned because it has been unable to discredit the initial source and additional information from the source.

The 19 operatives were to place improvised explosive devices in the subways using briefcases, according to two sources. Police Commissioner Ray Kelly said officers will continue to check bags, briefcases and strollers, and additional uniformed and undercover officers will be riding in individual subway cars.

I'm a little confused here - were FBI agents in Iraq? If this "source" was arrested in the U.S., why refer to him as an "Iraqi insurgent"?

Question: If he was arrested in Iraq and his information helps thwart a terror attack in New York, does that help or hurt the case for U.S. troops remaining in Iraq?