TOWERING THREAT: French soldiers patrol the Eiffel Tower in Paris on Sunday. The State Department is cautioning Americans traveling in Europe to be vigilant because of heightened concerns about a terrorist attack, but the U.S. has not told citizens to forgo travel to Europe. (Associated Press)

TOWERING THREAT: French soldiers patrol the Eiffel Tower in Paris on Sunday. The State Department is cautioning Americans traveling in Europe to be vigilant because of heightened concerns about a terrorist attack, but the U.S. has not told citizens to forgo travel to Europe. (Associated Press)