Trade war

Many experts who follow US/Russian relations feel that when Reagan fired the traffic controllers it got Gorbachev's attention in a way that words could not. His action added to his credibility on other issues showing that he was not afraid to take a stand on principle. In a similar vein when Trump puts an import tax on China in an election year people like Kim in North Korea pay attention. With most American presidents foreign leaders know how to push their buttons to get them to back away from controversy. For the same reasons that the news people are frustrated with Trumps unorthodox behavior foreign leaders find him difficult to read but they know he is not afraid to go against the status quo. In the vernacular of the day he is not presidential and that concerns China and North Korea.