Guys, please calm down a little

The question is not so much about what exact percentage of hashing power the Chinese miners are controlling at the moment, though everything shows that they already control substantially over 51% of it. In any case, the Chinese government can at any moment pour enough resources (which they have with a vengeance) into mining if they think it worth the effort, and grab as much hashing power as they see appropriate. The questions which I think worthy of debating here are as follows. First, could the miners potentially make the transactions coming from the US substantially more expensive than all other transactions, or even totally discard them? And, second, is it ever possible to circumvent such discrimination should it happen for real, and if it is doable, how can it be done exactly?

Let's assume for a moment that the Chinese authorities do control Bitcoin mining, and they are eager to retaliate in the way I described (e.g. through raising fees)