As I said, it's a power imbalance, with "force" being in the economic-coercive sense, not the threat-of-physical-violence sense: "do this, or we won't let you sell anything to us, so no entrepreneur or investor who cares about 'size of market' will want anything to do with you, so you'll run out of GDP-growth and your economy will stagnate." See: Cuba. Alternatively, "we'll take away the sweet deal [usually a tariff on a more productive country] that you've built your entire economy upon." See: Cambodia.
Don't see China in either case, though--they're in a very special position; they have enough population to sell to on their own, but they're also heavily invested in American credit markets. America has economic-coercive power over them in the same way a bad debtor has economic-coercive power over their credit card company: if you default, they get screwed, so they want to make sure they don't do anything that screws up your ability to pay them back, even if it would be good for their profit otherwise.
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Also, as a note on framing: by thinking of the conversation as "jumping around," you're committing the Fallacy Of Linear Discourse In A Threaded Comment System (which I obviously just made up the name for, though I've heard it described before.)
Posts organized into a tree-structure are by default tangents from, not replies to, their parent. Only one subthread of each thread needs to actually "continue the conversation" -- the rest can have whatever other purpose their authors wish. Soapboxing for their personal issues, pedantry and pointing out typos, wordplay on the parent's speech, &c.
It's a self-perpetuating fallacy, since people who think threaded conversations are linear actually cause this jumping-around in the first place, by trying to force "the" conversation "back to the topic at hand."
This confuses enough people that I'm trying to work out a threaded-commenting UI where replies move down--like a message board--and only tangents move to the right (and default to closed.)
Notice that this post is actually two posts: one is a reply, and then the other, after the line, is a tangent. Don't they seem like they should be treated separately by the UI? :)