Trump wants to reopen and modify some aspects of existing international agreements. Everyone just waves the agreements and say we already have a deal. He is using the powers in his hands to force partners to the negotiating table.
It is nothing more to it than that. There is an entire group of economists who have this thinking. The partners need to work with him, give here take there and it will all blow over and settle down.
Trump is doing nothing different than what he has said for years and during the campaign. Why are people surprised.