All things considered the US's posturing should be more aggressive regarding China. I mean I know the rhetoric is that China holds all the cards, but honestly they have a lot of issues to work out. Wealth distribution is completely broken, the population is about to have a severe decline thanks to the idiotic "One Child" policy that saw people selecting for boys instead of girls - never mind that girls have babies not boys, and of course China can't call in the debt America has without destroying their best customer. Also it doesn't matter if they have a lot of people, if those people are poorly trained and old(er).
And I'm saying this just to be aggressive, the simple point is that as Putin has shown you can't be wussy about this sort of thing. If you allow these kinds of excursions they will only get bolder and worst until by the time you do deal with it's a massive mess you could have avoided. But we'll see - diplomacy has it's place, but sometimes you need less to walk quietly and more to be swinging with a massive stick.