Nothing would happend from this. China and other might raise their alarm, but nobody would raise their own weapons without proof for something really happning outside of twitter.
In the meanwhile Trump would appear after some minutes on TV, youtube, and whatever other channel they have around, proofing that he is not sending the tweets, while twitter would do their stuff.
You are an optimist. We only need one mistake for things to get out of control. The history of known close calls is eye opening[1]. Similarly with this particular China example, it only takes one person to make a miscalculation.
I'm a realist. This list proofes that people are not as stupid as alarmists make them. At the end of the line, there are always people asking the relevant questions, because it's their f*ing job to do that.
In the meanwhile Trump would appear after some minutes on TV, youtube, and whatever other channel they have around, proofing that he is not sending the tweets, while twitter would do their stuff.