6:12 PM Update: New York City Police Department is reducing its deployment of its forces back to normal. See here.
New York State Department of Health fact sheet on Dirty Bombs, what they are, what to do if one detonates, etc. Read here.
California Yankee offers some insight into what it would be like if (God Forbid) a dirty bomb is exploded.
9:07AM Update: Israeli terrorism expert tells One Jerusalem that he knows of no source other than Debka that is reporting this threat.
7:33 AM Update: Homeland Security - "We are closely monitoring the situation."
Very public police survalience of vehicles in Manhattan continues. Is this really a response to a DEBKA report? DEBKA that is not the most reliable source in town?
Ed Morrissey has good overall analysis at Captain's Quarters.
Riehl's World View has more.
11:33 Update: FBI and Homeland Security say there is no specific threat to New York. Information was posted on web site and picked up by Israeli site that monitors jihadist sites.
UPDATE: Mayor Bloomberg just said the threat level has not changed.
There are several reports tonight that New York City police are increasing activity in Mid-Town Manhattan and at bridges and tunnels in response to unconfirmed reports that there might be a nuclear device coming into the city.
Channel 11 news just reported that there is talk of extending police shifts. They showed film of police searching vehicles near Penn Station.
Cahnnel 9 My News and CBS Radio also carried story. See myFoxNY here.