You may notice increased security still on roadways around the District and northern Virginia Monday morning.
The country is still on high alert for the potential terror threat that came early last week. The threat had a window stretching from September 10 through September 12.
Law enforcement this weekend aggressively investigated any unusual behavior. Stolen vehicles in both the D.C. and New York metro areas prompted large-scale searches. Two commercial flights into New York were shadowed by fighter jets after passengers spent unusual amounts of time in the bathroom. In Kansas City, a gate was closed and a passenger was removed after suspicious material was found in his luggage.
Investigators continue to chase a tip that al-Qaida may have sent three men to the U.S. on a mission to detonate a car bomb in either Washington or New York. But officials Sunday said they've found no evidence al-Qaida sneaked anyone into the country.
D.C. police will remain on 12-hour shifts at least through Wednesday.
Several threatening posts appeared on the White House Facebook page, with images of Osama Bin Laden promising new attacks.
Counterterrorism adviser John Brennan said officials are ``looking at travel data, other types
of pieces of information and trying to correlate them against that reporting that has come in.''
``It's not confirmed but we are not relaxing at all,'' Brennan said Sunday. ``This is a 24/7, round-the-clock effort by all elements of the U.S. counterterrorism community both here in the United States as well as abroad.''