Defense Secretary Donald Rumsfeld said a threat of possible year-end terror attacks against the United States was serious, while other parts of the world were also on alert on Christmas Eve. Washington told its citizens in Bahrain there was a terror threat in the Gulf Arab state during the Christmas holidays, Turkish police issued a similar alert to companies and banks in Istanbul, and Indonesian police stepped up patrols in Jakarta. On Tuesday, the Pentagon carried out an exercise to prepare for a terror attack and widened warplane patrols in the United States amid fresh concern about threats to nuclear power plants and other vital infrastructure. Full Story