I would argue the opposite. US backing of Japan has allowed them to maintain an insular chauvinism relative to their neighbors that has put them in weak diploma

I would argue the opposite. US backing of Japan has allowed them to maintain an insular chauvinism relative to their neighbors that has put them in weak diplomatic and economic position when faced with China. If they had instead become more tightly coupled with their neighbors like Korea and Taiwan, they’d be in a much better position to check the power of a rising China (think Germany within the context of the EU). Of course this isn’t entirely Japan’s fault, as the US funded and backed right-wing nationalists in just about all of these countries, so they could play them off each other as was useful to their interests.