WASHINGTON — Defense Secretary Mark T. Esper was fired by President Trump on Monday, the latest casualty in the president’s revolving door of top national security officials who fell on the wrong side of their boss.
Mr. Trump announced the decision on Twitter, saying in an abrupt post that Mr. Esper had been “terminated.”
Mr. Trump wrote on Twitter that he was appointing Christopher C. Miller, described by the president as the “highly respected” director of the National Counterterrorism Center, to be acting defense secretary. He will be the fourth man to lead the Pentagon under Mr. Trump, who made a point of noting that Mr. Miller has been approved by the Senate already.
Mr. Miller is a former Army Green Beret who previously served as the top counterterrorism policy official in the Trump White House’s National Security Council.
Mr. Esper’s downfall had been expected for months, after he took the rare step in June of disagreeing publicly with Mr. Trump and saying that active-duty military troops should not be sent to control the wave of protests in American cities. The president, who had threatened to use the Insurrection Act to do exactly that, was furious, officials said.
Mr. Esper’s spokesman tried at the time to walk back the damage, telling The New York Times that Mr. Trump did not want to use the Insurrection Act, either, or else he would have invoked it already. “We fail to see the disconnect,” said Jonathan Hoffman, a spokesman for Mr. Esper.
White House officials disagreed.
Mr. Esper, 56, a former secretary of the Army and a former Raytheon executive, became defense secretary last July after Mr. Trump withdrew the nomination of Patrick M. Shanahan, the acting defense secretary, amid an F.B.I. inquiry into allegations from Mr. Shanahan’s former wife that he punched her in the stomach. Mr. Shanahan denied the accusations.
Mr. Shanahan had been standing in for Jim Mattis, who resigned as defense secretary in 2018, citing his own differences with the president.
Mr. Esper had taken pains to hew to the Trump line during his tenure. But concern over invoking the Insurrection Act to send active-duty troops to battle protesters across the country is deep in the Pentagon. Under heavy public criticism, Mr. Esper ultimately broke with the president.
Mr. Trump’s has referred to Mr. Esper as “Mr. Yesper.” But the insult is ironic by itself, since it was the defense secretary’s public break with the president during a news conference in June in which he spoke against use of active-duty American troops to quell civil unrest that infuriated Mr. Trump to begin with. Those comments came after he had accompanied Mr. Trump on his walk across Lafayette Square outside the White House, where protesters had just been tear-gassed, prompting condemnation from former military and civilian Defense Department officials.
By midsummer, Mr. Esper was walking a fine line to push back on other contentious positions involving the military that Mr. Trump had taken.
The Pentagon, without once mentioning the word “Confederate,” announced in July that it would essentially ban displays of the Confederate flag on military installations around the world.
In a carefully worded memo that Defense Department officials said was written to avoid igniting another defense of the flag from Mr. Trump, Mr. Esper issued guidance that listed the types of flags that could be displayed on military installations — in barracks, on cars and on signs.
The guidance did not specifically say that Confederate flags were banned, but they do not fit in any of the approved categories — and any such flags are prohibited.
After the fateful events of June, Mr. Esper sought to fly under the radar, avoiding the media and keeping a low profile to prevent being pulled into election politics.
Mr. Esper traveled often beginning in early summer, including overseas trips to North Africa, the Middle East and India.
But the secretary deliberately limited his public comments while on the road.
And when he did speak in public, when either abroad or in Washington, it was often in prerecorded remarks, on safe subjects (bashing China and Russia on the Africa trip) or in friendly venues (a question-and-answer session on military readiness at the Heritage Foundation, where Mr. Esper served as chief of staff earlier in his career).
Yet, on the single biggest issue of 2020 — the coronavirus pandemic — history may show that Mr. Esper has, by far, outperformed his boss, who largely refused to wear a mask and contracted the coronavirus during an outbreak at the White House. Mr. Esper, by contrast, has strictly adhered to guidelines from the Centers for Disease Control and Prevention on wearing a mask when unable to keep a recommended social distance.
At a Pentagon virtual town-hall-style meeting, Mr. Esper responded to a sailor on the aircraft carrier Gerald R. Ford, who complained the required social distancing onboard the ship was hurting morale.
“It is tedious — I understand that,” Mr. Esper said. “But I think it’s showing, in terms of the Navy’s results in terms of infection rates, that they’re doing a very good job.”