Some analysts and former policy makers were blunt in saying that a failure to come to Japan’s aid in a clash over the Senkakus/Diaoyu islands could spell the end of the two nations’ postwar alliance.What - they're gonna hike defense spending beyond the current measly 1% of GDP? I have my doubts. Uncle Sam's the only game in town unless the Japanese are willing to make sacrifices. The Yamato spirit isn't dormant - it's extinct.“If Japan is attacked, and the Americans decline to respond, then it is time from the Americans to pull out” of their bases here, Mr. Miyake said. “Without those bases, America is not going to be a Pacific power anymore. America knows that.”
They pay for all the US bases in Japan so they can just re-direct that money into weapons systems.