China has overwhelming numbers, any Chinese citizen could be given a gun and told kill or be killed.
China also has the ability to mass produce anything cheaply(weapons included.)
EDIT: China was the first to mass produce a weapon, and they are likely to be the last when they finally decide to take over the world.
bluemeanie1, You should really edit/append your posts.
Having four replies by a single person(with nobody in between) is nonsense.
I don't believe China would ever go this way. The main problem for the Chinese govt is to keep its population fed and in employment for without that their power would be at risk. Imagine a couple of hundred million poor hungry people trying to make do. Dumping US Treasuries would cripple the US, probably also the world and definitely the Chinese themselves. What it looks like they are doing, is transitioning away. Deals with Europe, Australia and Russia that aren't denominated in US dollars. Buying gold. Buying farmlands overseas. China has traditionally been a country that wants to keep others out, but slowly it has relaxed its borders & ideologies, however it is a big jump to see it taking over the world anytime soon.