Vietnam, Afghanistan, Iraq, coup after coup in South America - you think Tiananmen was more reprehensible than any of these?
I'll also remind you Tiananmen was internal, whereas all of our wars are just that - wars. Directed against other nations.
edit: to clarify, I don't see how Tiananmen suggests China will go to war, but I do see how a sordid history of spurring violence across the globe suggests the US will go to war again.