WASHINGTON (CNN) -- A day after dozens of peace activists boarded double-decker buses and a taxi to travel from London to Baghdad in hopes of preventing bombing by the U.S. and its allies, the Bush administration criticized their efforts. "We would not recommend that people allow themselves to be used by a tyrant and a dictator who has a history of doing horrible things to even his own people as well as his neighbors," White House Chief of Staff Andrew Card told Fox News Sunday. "So this is not the time for people to call themselves human shields." On Saturday,...