The art of the deal always seemed to be, (1) create a situation unfavourable to your opponent. (2) exploit their temporary weakness to force a coercive one sided deal.

Trump seems to be able to do that well enough in the normal business world. The thing is when it comes to countries its harder to get them to roll over because if a dictator looks too weak its off with their head. If you give a dictator the choice of ruling over an impovrished country or dying in a coup, they are going to choose the former. On top of that its hard to make international coercive deals stick. In the normal business world, you can sue if someone reneges. When it comes to countries, what are you going to do? Whine to the UN? Good luck with that. Countries can stick with deals when it suits them and forget about them when it no longer does. At worse that may not make countries want to make deals in the future, but if it was a coercive deal that doesnt matter much.