WASHINGTON — In a tweet Nov. 9, President Donald Trump announced he fired Defense Secretary Mark Esper and appointed Christopher Miller, the director of the National Counterterrorism Center, as acting secretary.

Trump’s tweet follows conflicting media reports over the past several days about the fate of Esper, who became secretary of the Army in 2017 and was sworn in as secretary of defense in July 2019. In recent months, Esper had been at odds with Trump over the president’s call to deploy military forces to quell protests in the United States. Esper also clashed with the White House over the renaming of military bases named after Confederate leaders.

Congressional Democrats criticized the decision to terminate a high-level cabinet official so close to the end of the current administration. “Trump is creating a dangerously unstable national security environment during this transition period. Adversaries are watching,” Sen. Chris Murphy (D-Conn.) tweeted.

Rep. Adam Smith (D-Wash.), chairman of the House Armed Services Committee, said in a statement that terminating Esper “destabilizes the Pentagon ahead of the presidential transition.”

Periods of presidential transition “leave our country exposed to unique threats,” said Smith. “Until President-Elect Biden is sworn into office next January, it is imperative that the Pentagon remain under stable, experienced leadership.”

Miller will be the fifth Pentagon chief to serve under Trump, although only Jim Mattis and Mark Esper were confirmed by the Senate. Patrick Shanahan and Richard Spencer served as acting secretaries. 

Senate Armed Services Committee Chairman Sen. Jim Inhofe (R-Okla.) said in a statement he spoke with Miller on Monday and plans to work with him to “maintain stability at the Pentagon, particularly as we work to enact the 60th annual National Defense Authorization Act.”

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...