Rep. Mica worried transit systems will be targeted for bin Laden retaliation

Homeland Security Secretary Janet Napolitano said she was also concerned about the possibility that transportation might be targeted in the aftermath of bin Laden's death. But Napolitano said that she did not have any "credible threats" that warranted attention.

"We remain at a heightened state of vigilance, but the Department of Homeland Security does not intend to issue an NTAS alert at this time," Napolitano said in a statement. "I have been clear since announcing [the National Terrorism Advisory System] in January that we will only issue alerts when we have specific or credible information to convey to the American public. However, our security posture, which always includes a number of measures both seen and unseen, will continue to respond appropriately to protect the American people from an evolving threat picture both in the coming days and beyond."
Transportation agencies in New York and Washington, D.C., said Monday they had increased security.

"Metro is coordinating with TSA and MPD on security; users will see an increase in # of officers throughout system (trains & buses)," D.C. Mayor Vincent Gray said on Twitter. "MPD also increasing security patrols near local houses of worship, although no specific threats yet received."

Meanwhile, the TSA said it would be business as usual at the nation's airports.

"TSA continually evaluates the latest threats and screening measures which are implemented based on the latest intelligence," the agency said in a statement emailed to The Hill.

"As always, passengers may notice a variety of security measures at U.S. airports to include the use of explosives detection technology, physical bag checks, random gate screening, canine teams and behavior detection officers. We ask the traveling public to remain vigilant and report any suspicious activity to the authorities."