http://www.cnn.com/2006/US/09/12/usaf.weapons.ap/index.html
CNN published an article today announcing that the US Air Chief, Secretary Michael Wynne. said, "Nonlethal weapons such as high-power microwave devices should be used on American citizens in crowd-control situations before being used on the battlefield"
The object is basically public relations. Domestic use would make it easier to avoid questions from others about possible safety considerations. Read the article on CNN