Trump did not just announce that he was “de-certifying” Iran’s compliance with the nuclear deal. He announced that Iran was from now on going to be in the bullseye of the US military.
President Trump has been notoriously inconsistent in his foreign policy. He campaigned on and won the presidency with promises to repair relations with Russia, pull out of no-win wars like Afghanistan, and end the failed US policy of nation-building overseas. Once in office he pursued policies exactly the opposite of what he campaigned on. Unfortunately Iran is one of the few areas where the president has been very consistent. And consistently wrong.