The air warfare of World War II was a major component in all theaters and, together with anti-aircraft warfare, consumed a large fraction of the industrial output of the major powers. Germany and Japan depended on air forces that were closely integrated with land and naval forces; the Axis powers downplayed the advantage of fleets of strategic bombers, and were late in appreciating the need to defend against Allied strategic bombing. By contrast, Britain and the United States took an approach that greatly emphasised strategic bombing, and (to a lesser degree) tactical control of the battlefield by air, as well as adequate air defences.