Rex Tillerson was poorly cast as secretary of state. The veteran oil executive never grasped some of the essentials of diplomacy, including the importance of public communication. …

None of those weaknesses, however, appear to explain why President Donald Trump abruptly dismissed, via tweet, Tillerson on Tuesday — the last of many humiliations the president inflicted on his top diplomat. Rather, Trump suggested that he and Tillerson were “not really thinking the same” on key foreign policy issues, which is true. Tillerson resisted the president’s steps toward voiding the nuclear deal with Iran and the Paris climate treaty, and opposed moving the U.S. Embassy in Israel to Jerusalem. When Tillerson spoke in favor of diplomacy with North Korea, Trump tweeted that he was wasting his time; then, the same day Tillerson said negotiations with the regime of Kim Jong Un might be a long way off, Trump agreed to a summit meeting.

Most disturbingly, Trump would not back the tough stances that Tillerson struck, with ample reason, against the misdeeds of Russian ruler Vladimir Putin. Most recently the secretary said he agreed withthe British government that Russia should be held responsible for an attack on British soil with deadly nerve gas. But Trump on Tuesday was equivocal, suggesting the administration still needed to “get the facts straight.”