In 1950 Japan finally replaced the U.S. soldiers with their own police officers. Ever since World War II they have tremendous fear that the U.S. military is hostile. The United States occasionally gives Japan support in the form of supplies, transportation and medical necessities when needed. The United States and Japan established a peace treaty that allowed free international exchange. Bush wants Japan to help in defenses more actively.
Japan happens to be the third largest defense in the world.
They also pay 41 percent of stationing fees of U.S. soldiers. Since the 1960s some people have believed that the United States should help pay for the stationing fees as well as other fees. United States and Japan combined have nearly all of the global savings in the world. It's currently a peaceful existence between the countries. An ally in today's world is a necessity.