The Obama administration on Sunday warned Americans of potential terrorist threats in Europe and urged them to be vigilant in public places, including tourist spots and transportation hubs.
A State Department travel alert advises U.S. citizens living or traveling in Europe to take more precautions about their personal security. The alert is one step below a formal travel warning advising Americans not to visit Europe.
"Current information suggests that al-Qaida and affiliated organizations continue to plan terrorist attacks," it said. "European governments have taken action to guard against a terrorist attack and some have spoken publicly about the heightened threat conditions."
It noted in particular "the potential for terrorists to attack public transportation systems and other tourist infrastructure."
"U.S. citizens should take every precaution to be aware of their surroundings and to adopt appropriate safety measures to protect themselves when traveling," the department said.
U.S. and European security experts have been concerned for days that terrorists may be plotting attacks in Europe with assault weapons on public places, similar to the deadly 2008 shooting spree in Mumbai, India.
"The terrorist threat exists, and could hit us at any moment," the French defense minister, Herve Morin, said in an interview published Sunday. "Networks organizing themselves to prepare attacks are constantly being dismantled around the world. It is good for the French to know this," he was quoted as saying in the daily Le Parisien.
he U.S. notice said terrorists "may elect to use a variety of means and weapons and target both official and private interests" and noted past attacks against subways, rail systems and aviation and maritime services.
"U.S. citizens should take every precaution to be aware of their surroundings and to adopt appropriate safety measures to protect themselves when traveling," according to the alert.
The alert fell short of a formal travel warning, which could have broader implications including a stronger likelihood of canceled airline and hotel bookings, and wasn't intended to urge travelers to stay away from public places. Europeans and some members of the Obama administration had viewed that as an overreaction.
The alert could hurt European tourism and affect business travel. But there hadn't been strong opposition to the proposed alert from European leaders, who privately have been advised of the impending action, a European official said.
There are hundreds of thousands of Americans in Europe at any one time, including tourists, students and businesspeople. For insurance and liability reasons, many U.S. college and university study-abroad programs will not send students to countries for where a warning is in effect.
U.S.. intelligence officials believe Osama bin Laden is behind the terror plots to attack several European cities. If true, this would be the most operational role that bin Laden has played in plotting attacks since Sept. 11, 2001.
Eight Germans and two British brothers are at the heart of an al-Qaida-linked terror plot against European cities, but the plan is still in its early stages, with the suspects calling acquaintances in Europe to plan logistics, a Pakistani intelligence official said Thursday. One of the Britons died in a recent CIA missile strike, he said.
The Pakistani official said the suspects are hiding in North Waziristan, a Pakistani tribal region where militancy is rife and where the U.S. has focused many of its drone-fired missile strikes.