The sound of anti-aircraft fire filled Tripoli Sunday night as U.S. and allied forces from France and Britain entered their second day of airstrikes against Col. Muammar Gaddafi’s regime. Rebels cheered as Western fire took out regime targets earlier in the day. A French aircraft gunned down a phalanx of Gaddafi tanks that were headed for Benghazi, giving temporary relief to the rebel capital. Adm. Mike Mullen, chairman of the Joints Chief of Staff, called the campaign " so far very effective." However, there is disagreement among Western powers about the end goals of the operation. France, which has taken the most aggressive tone, said it was committed to ousting Gaddafi, who has threatened a " long war" in retaliation, while American officials have continued to express hesitance about being drawn into another potentially open-ended conflict.