 Slim's efforts were aided by improvements to the Allied lines of communication.By October 1944, capacity on the North-East Indian Railways had been raised from 600 tons a day at the start of the war to 4,400 tons a day.The Allied Eastern Air Command, which consisted mainly of Royal Air Force squadrons but also several units of the Indian Air Force and bomber and transport units of the United States Army Air Forces (USAAF), had gained air superiority and this allowed the Allies to employ new tactics, relying upon air support and aerial resupply of troops.