Before the Korean War, the primary mission of Lt. Gen. George E. Stratemeyer's Far East Air Forces was air defense of the Japanese homeland. Most of the aircraft constituting Stratemeyer's inventory were interceptors, not designed for the type of combat that would be required now that the United States was joining in the UN effort to end the war in Korea. The Joint Army/USAAF doctrine of 1946, known as Field Manual 31-35, Air Ground Operations, was also considered outdated in the present circumstance. A new approach to warfighting had to be developed in response to the strong influence of General Douglas MacArthur and other of his air officers in the Army-dominated General Headquarters Far East Command. Close air support of the ground forces as provided by Fifth Air Force came at some cost, and tempers flared in the process, but the air commanders in Korea never deprived the ground commanders of close air support if it was needed. Indeed, without the close air support provided to the airmen, the ground campaign would have been a much more bloody and difficult affair than it was.