President George W. Bush personally gave the go-ahead for the U.S. attack on Iraqi insurgents that began Monday in Fallujah, White House Spokesman Scott McClellan said. McClellan said that Bush held a video-conference call on Friday with his national security team, and "signed off" on the start of the offensive after meeting with Secretary of Defence Donald Rumsfeld early Monday. According to U.S. General George W. Casey, some 15,000 troops are involved in the offensive, which was described by the Pentagon as the U.S. military's biggest urban battle since the Vietnam War. The Pentagon has called the offensive "Operation Phantom Fury". Casey said that in consultation with Iraqi Prime Minister Iyad Allawi forces on the ground were calling it "Al Fajr" which means "The Dawn". --SP 2218 Local Time 1918 GMT