The only nation with the military strength to stand up to China is the U.S. and since America imports a ridiculous amount of goods from China it will probably not act. The impact on their economy would be to negative, especially on top of the current slump it is in. So, China would probably be safe in invading south east Asia

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"When I give food to the poor they call me a saint. When I ask why the poor have no food, they call me a communist."