I wouldn't say that Japan is a world power now, not even economically anymore. The Japanese certainly could fight an extended war, as they fought eight years continuously from 1937 onwards. Claiming that they weren't a World Power is like claiming that the US wasn't one because of it's isolationism between the wars and deliberately limiting it's empire building then in the close regions of Caribbean and Central America. Desperately clinging to tiny specks of rock in the Pacific as the US systematically exterminated the entire Imperial Japanese Navy from June 1942 onwards isn't a world power. Their 1937-1941 time frame was successful because they were beating up on powers even less powerful than they were-British colonies with virtually nothing to defend themselves with, and China, which hadn't been significant for at least forty years by that point. They only had a period of success from December 1941 to June 1942 because the US industrial base hadn't gotten up to speed yet. There were never anything beyond a regional power by the standards of the time. US has done zilch to guarantee peace in the area. First it killed and helped to kill millions, afterwards it hasn't stopped a single war, just at worst poured more gasoline in the flames like when it supported the Khmer Rouge in the 1980s. When Cambodia and Thailand have been fighting over the strategically placed border temples, mainly as a result of internal Thai politics, what has US done? Piously asked for constraint on both sides and that's it. I'm sorry, you appear to not know what you're talking about. Feel free to bother knowing about ANZUS, the 1953 US-South Korea mutual defense treaty, the 1951 US-Japan Mutual Security Treaty, the 1951 US-Phillipines Mutual Defense Treaty, and the Taiwan Defense Act of 1979, before you say that "the US has done nothing." China hasn't conquered a neighbour since Tibet in 1950 (if we accept, like I do, that Tibet was an independent nation before that) and is extremely unlikely to do so in anytime in the future. The closer it's neighbours become to China economically, the greater havoc any military action against them would cause for China's own economy. China's rulers, in the end, are after stable growth, and if China would be fighting it's neighbours militarily, then that stability and growth that lead to internal peace and continuation of the current rule would go out of the window. Wow, wrong AGAIN...sure, China, hasn't conquered any of its neighbors since 1950, but that's mainly because its military is so incompetent that it couldn't handle Russia and Vietnam. Note: China is the only major power to have started wars in Asia since the end of the Vietnam War, not to mention it's insistently aggressive attitude towards the South China Sea and the countries that also exist there.