What was a focus of Billy Mitchell in military strategy?

Billy Mitchell was a pioneer in military aviation strategy and is best known for advocating the importance of air power in modern warfare. His focus was on improving doctrinal concepts and strategy related to the use of aviation in military operations. He believed that air power was a crucial component of national defense and could be decisive in warfare. Mitchell promoted the idea that air superiority could dominate the battlefield and reshape military tactics, leading to strategies that integrated air forces with ground and naval operations. His emphasis on developing strategic concepts for air power significantly influenced how military leaders viewed aviation's role in warfare.

The other options, while important aspects of military strategy, do not capture the essence of Mitchell's contributions and focus as accurately. Strengthening naval forces and improving ground troop tactics were significant military considerations but not specific to Mitchell's advocacy for air power. Increasing the size of the Air Corps, although related to his mission, isn't the core focus of his contributions, which were more about strategic integration and doctrinal influence rather than simply expanding the size of an existing military branch.