The leading theorist of air power was Italian general Giulio Douhet, who believed that future wars would be won or lost in the air. The air force would carry the offensive, and the role of the ground forces would be defensive only. Douhet's doctrine of strategic bombing meant striking at the enemy's heartland—his cities, industry and communications. Air power would thereby reduce his willingness and capacity to fight. At this time the idea of the aircraft carrier and its capabilities also started to change thinking in those countries with large fleets, but nowhere as much as in Japan. The UK and US seem to have seen the carrier as a defensive weapon, and their designs mirrored this; the Japanese Imperial Navy seem to have developed a new offensive strategy based on the power projection these made possible.