In late-1972 the Nixon Administration ordered an all-out air offensive against North Vietnam. The bombing raids, codenamed Operation Linebacker II, began on 18 December 1972 involving heavy attacks by almost every strike aircraft the US had in theater, with the B-52 playing a prominent role. The initial plan scheduled attacks for three days. Along with heavy strikes by USAF and Navy tactical aircraft, 129 B-52s in three waves (approximately four hours apart) from the 307th Strategic Wing at U-Tapao RTNAF and B-52Ds and B−52Gs of the 43d Strategic Wing and the 72 Strategic Wing (Provisional) both at Andersen AFB. The U-Tapao-based B-52Ds were able to carry more bombs and perform more sorties than the other units which operated less capable versions and had to fly much further to reach targets in North Vietnam.