U.S. and Vietnamese military commanders were reported by reliable military sources tonight to have ordered an extension of the 30-hour Christmastruce in the Vietnamese war. They said the U.S. Commander in Viet Nam General William C. Westmoreland, ordered U.S. forces to continue the cease-fire until further notice except in self-defence and that the Vietnamese Defence Minister, General Nguven Huu Co., had issued similar orders to Vietnamese forces. The original 30-hour truce ended at midnight.