“Tactics programmed for the SIOP are in two principal categories,” the head of the Joint Chiefs later explained, “the penetration phase and the delivery phase.” SAC would attack the Soviet Union “front-to-rear,” hitting air defenses along the border first, then penetrating more deeply into the nation’s interior and destroying targets along the way, a tactic called “bomb as you go.” Great Britain’s strategic weapons were controlled by the SIOP, as well. The Royal Air Force showed little interest in SAC’s ideas about counterforce. The British philosophy of strategic bombing had changed little since the Second World War, and the RAF’s Bomber Command wanted to use its nuclear weapons solely for city busting. The SIOP respected the British preference, asking Bomber Command to destroy three air bases, six air defense targets, and forty-eight cities.”