The problem Donald has now is he cannot work with the free world to punish countries with sanctions anymore. If he imposed a sanction on Russia or Iran - will Europe, Mexico, Canada etc follow? I am doubting it, unless it helps their own causes. Not for Trump’s ego. Or he will have to negotiate to give a lot up to get support from countries that used to do it all for free.
He has given up a lot of world power in only a few months.