News

During his first term, Trump dismissed both of his Secretaries of Defense:

• Trump's first Secretary of Defense, Jim Mattis

who was generally regarded as a strong pick for the office

was dismissed after he announced that he would resign over a decision Trump was making.

> On December 19, 2018, Trump announced immediate US withdrawal from Syria, over his national security advisers' objections.[133] Mattis had recently said that the US would remain in Syria after ISIL's defeat to ensure it did not regroup. The next day, he submitted his resignation after failing to persuade Trump to reconsider.[134][135] His resignation letter contained language that appeared to criticize Trump's worldview—praising NATO, which Trump has often derided, and the 79-nation anti-ISIS coalition that Trump had decided to leave. Mattis also affirmed the need for "treating allies with respect and also being clear-eyed about both malign actors and strategic competitors" and remaining "resolute and unambiguous" against authoritarian states such as China and Russia. He wrote that Trump has "the right to have a Secretary of Defense whose views are better aligned with [his] on these and other subjects."[136][137] His resignation triggered alarm among historical allies.[138] In his 2018 resignation letter, Mattis called both Russia and China "authoritarian models" rivaling US interests.[139] Mattis's letter said his resignation would be effective February 28, 2019.[140] Three days later Trump moved Mattis's departure date up to January 1, after becoming angered by the implicit criticism of Trump's worldview in Mattis's letter.[141] On January 2, 2019, Trump criticized Mattis's performance as secretary of defense and said he had "essentially fired him."[142]

• Trump's replacement, Mark Esper, was fired via Trump tweeting:

  After Trump lost the 2020 presidential election to Joe Biden, Trump launched a months-long effort to challenge the election outcome and remain in power, claiming that the election had been "stolen" from him.[284] In his subsequent memoir, published in 2022, Esper wrote that Trump's effort "was a national embarrassment that undermined our democracy, our credibility, and our leadership on the world stage."[284]

  On November 9, 2020, days after his election loss, Trump tweeted that Esper was "terminated," and that he had been replaced by Christopher C. Miller, the director of the National Counterterrorism Center who would serve as Acting Secretary of Defense.[285] Esper had written his resignation letter four days earlier, when a winner had not yet been determined.[286]

  On January 2, 2021, days before the end of Trump's term and the inauguration of Biden, Esper, along with all other living former secretaries of defense, published a Washington Post op-ed piece in January 2021 that rebuked Trump's effort to alter the election results, and said there was no role for the military to change them. The group's piece appeared days after Trump ally Michael Flynn, an ex-Army general, and reportedly Trump himself, discussed the possibility of declaring martial law and attempting to stay in power. The group wrote: "Our elections have occurred. Recounts and audits have been conducted. Appropriate challenges have been addressed by the courts. Governors have certified the results. And the electoral college has voted. The time for questioning the results has passed; the time for the formal counting of the electoral college votes, as prescribed in the Constitution and statute, has arrived."[287] Esper later wrote that Trump's behavior on January 6, when a mob of his supporters, incited by the president, attacked the Capitol and disrupted the counting of the electoral votes, "threatens our democracy."[288]

That being said, in both cases, it sounds like it was due to them disagreeing with him. As far as I know, Hegseth has not gotten into a major disagreement with Trump.