And to add insult to injury, Tillerson was basically an afterthought in that tweet, which first introduced Trump's new chosen top diplomat, CIA Director Mike Pompeo.
According to NBC News, senior State Department officials said that there were long-standing tensions between Tillerson and Trump, and that former Exxon Mobil CEO Tillerson learned that he was canned from that tweet just before 9 a.m. Tuesday.
NBC News reported that White House chief of staff John Kelly spoke with Tillerson by phone on Friday and told him that Trump intended to ask Tillerson to "step aside," according to two sources familiar with the situation.
Kelly did not provide an exact date or time for that change, according to those sources.
The Associated Press reported that during that call from Kelly, Tillerson only was told that Trump might tweet something that would concern him, but was not told what the tweet would say or when it might be posted.
In a prepared statement issued Tuesday, the State Department's press office suggested that Tillerson was blindsided by the announcement of his being axed.
"The Secretary had every intention of remaining because of the tangible progress made on critical national security issues," the press office said. "The Secretary did not speak to the President this morning and is unaware of the reason, but he is grateful for the opportunity to serve, and still believes strongly that public service is a noble calling and not to be regretted."
The office added: "We wish Secretary-Designate Pompeo well."
NBC News reported in October that Tillerson was on the verge of quitting last summer because of policy disputes and clashes with the president.
Tillerson after a July 20 meeting had referred to Trump — who was not in attendance — as a "moron," according to NBC.
Tillerson later publicly claimed that "I have never considered leaving this post."
But he has refused to say whether or not he called Trump a moron.
In an Oct. 4 briefing, State Department spokesperson Heather Nauert said Tillerson did not use the word "moron" to describe Trump, the NBC report said. "The secretary did not use that type of language to speak about the president of the Unites States," Nauert said. "He did not say that."