On Saturday, a suicide bomber blew himself up on a pedestrian street in Stockholm, Sweden, killing himself and injuring two other people. Iraqi officials say that captured insurgents said this week that the suicide bombing was part of attacks being planned by al-Qaida against the U.S. and Europe during the Christmas season.
Even before the revelations from the captured Iraqi insurgents, U.S. counterterrorism officials were tracking threat streams from al-Qaida operatives hiding in Pakistan and Yemen.
There is specific intelligence of other attacks being planned against Europe during the holiday season, according to U.S. officials speaking on condition of anonymity to discuss security matters. While intelligence officials have not uncovered specific details of threats aimed at the U.S., they cannot be ruled out, the officials said.
Still, the spate of attempted attacks against the U.S. in the past year -- particularly the Nigerian man charged with trying to take down an airplane last Christmas -- has U.S. officials on high alert.
"We are concerned these terrorists may seek to exploit the likely significant psychological impact of an attack targeting mass gatherings in large metropolitan areas during the 2010 holiday season, which has symbolic importance to many in the United States," the joint FBI and Homeland Security bulletin said.
Earlier this month a Portland man was caught in an FBI sting operation as he allegedly planned to set off a bomb at a crowded Christmas tree lighting ceremony. And in October, al-Qaida's Yemeni offshoot -- which also claimed responsibility for the Christmas airliner attack -- tried to take down two cargo planes over the U.S. That plot was foiled after officials received a tip, including the packages' tracking numbers, from Saudi Arabian intelligence.
Counterterrorism officials said they could not discount potential threats from other terror groups, such as al-Qaida's offshoots in Iraq and the Islamic Maghreb, Pakistan and Somalia.
"Al-Qaida and other terrorist groups continue to seek innovative ways to conduct attacks and circumvent security procedures, and we remain concerned that the holiday season provides attractive opportunities for terrorists to target the homeland," the intelligence bulletin said.