Amid a heightened state of alert for terrorists, the U.S. government said Monday it will require international air carriers in certain cases to place armed law enforcement officers on flights over the United States. The Homeland Security Department said the directive, which is effective immediately, will further enhance security on commercial and cargo aircraft flying to, from and over the United States. “We are asking international air carriers to take this protective action as part of our ongoing effort to make air travel safe for Americans and visitors alike,” Homeland Security Secretary Tom Ridge said in a statement. Full Story