This aint some game and he certainly wouldnt use a tweet to signal to his enemies something along the lines of "bombing China = fake news" just so they let their guard down whilst he proceeds to then bomb China.

Not only would it be terrible in terms of the optics and his reputation but the strategy doesnt even make sense.

If you are going to misdirect the enemy you need to actually direct attention elsewhere.. not just say "i wont be doing that, promise".

If he truly was going to be going the martial law route he wouldnt mention it at all and let the rumors spread, keeping them guessing is far more powerful than tweeting a lie about your next move.