Reporting from Washington — After arrests in Europe and sting operations in the U.S., intelligence agencies have been on edge this holiday season over concerns that terrorist organizations are setting their sights on easier-to-hit targets such as subways, trains and large public gatherings.
Federal and local authorities have responded with demonstrations of force and high-profile arrests to deter would-be plotters.
More bomb-sniffing dogs checked passengers on Amtrak train platforms. Security bulletins told local police to be on guard for attacks against sporting events, parades and religious activities. Authorities in Washington randomly checked subway riders' bags for explosives in the days before Christmas, and some officers carried assault rifles as they patrolled Metro stations.
The "enhanced measures" were a response to a heightened threat against trains, subways and buses, Homeland Security Secretary Janet Napolitano said the day after Christmas. Napolitano also said the agency in the last year had reached out and provided training to counter threats against "so-called soft targets — the hotels, shopping malls, for example."
The FBI also has brought charges in three undercover sting operations in the last three months. Authorities said suspects in Washington, Baltimore and Portland, Ore., attempted to collect explosives to bomb public places from people they thought were co-conspirators, only to be nabbed by undercover agents who had posed as domestic terrorists.
Authorities said the bomb plots were evidence that terrorists were changing their game plans.
Pressure from U.S. drone strikes in Pakistan and financial sanctions on Al Qaeda have "made it much more difficult for them to plan spectacular attacks," said Rick Nelson, director of the homeland security and counter-terrorism program at the Center for Strategic and International Studies.
"They are trying to expand their repertoire," Nelson said, to attacks that are "a lot less sophisticated but easier to execute."
On Wednesday, three men were arrested in Denmark for allegedly plotting to kill as many people as possible in the offices of a Copenhagen newspaper in retribution for the publication of a cartoon of the prophet Muhammad in 2006.
Al Qaeda in Yemen has gone public in encouraging American citizens to attack their own country, recruiting potential bombers through Internet video speeches by American-born cleric Anwar Awlaki and the publication of three issues of a slick English-language propaganda magazine called Inspire.
The online magazine discourages American Muslims from taking trips to training camps in Pakistan or Somalia that might land them in U.S. intelligence databases. Instead, articles encourage recruits to plan and launch attacks on American soil and offer examples of how to do it, such as using homemade bombs, ramming a truck into a crowd or shooting into a busy Washington restaurant.
The approach may seem hapless on the surface, but it can't be ignored, said Stewart Baker, the Department of Homeland Security's first assistant secretary for policy and the author of "Skating on Stilts: Why We Aren't Stopping Tomorrow's Terrorism."
The organizers of the Al Qaeda branch in Yemen know that even a failed attack such as the foiled package bomb plot in October will scare Americans and bring more attention to their cause, Baker said.
"They are not haunted by the need to do something as spectacular as 9/11," Baker said. "They seem completely unfazed by failure or looking stupid."
Soft targets aren't new targets, said Frank Cilluffo, director of the Homeland Security Policy Institute at George Washington University, but the success of the 2008 attacks on a posh hotel and other sites in Mumbai, India, gave militants new incentive to look at hitting things other than airplanes.
"The fact is, our surface transportation is not as secure as our air transportation," said Cilluffo, who added that random searches, increased police presence and bomb-sniffing dogs can go a long way toward deterring attacks. "But all of this is predicated on good intelligence. Good intelligence is the lifeblood. As much as we can invest in that environment is money well spent."
To encourage citizens to point out suspicious behavior, Napolitano has promoted a national initiative using the slogan, "See something, say something." Announcements can be heard on trains in Washington and even in Walmart stores across the country.
To collect and share information on tips, the Department of Homeland Security has helped fund and train staffs at 72 state and regional "fusion centers," where law enforcement officials with top-secret clearances can read high-level intelligence and analyze reports of suspicious activity from local authorities.