If you really wanted to start a war in China, the U.S. could make Taiwan into another South Korea. That would neceessitate a major retaliation from them. It'd be like their Cuban missile crisis.
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Now, set aside how war is bad and all the deaths would be terrible, but aren't you interested in seeing the U.S. in a war with an established country to see just how far ahead of everyone we are? Part of our bloated defense budget makes it so we're so far ahead of everyone else, we're like Superman in a china shop (no pun intended). The first Gulf War was easily won with kid gloves. Battling Al Queda and ISIS has been like going through a kid's hair with a lice comb.
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Who would step up to the plate and declare war on us, country vs country? China is too smart to do that.