President Biden intends to nominate Gen. Charles Q. Brown, the Air Force chief of staff, on Thursday to become the country’s most senior military officer, formalizing what had been one of the worst kept secrets in Washington.
If confirmed by the Senate, General Brown would be only the second Black man, after Colin L. Powell, to hold the job of chairman of the Joint Chiefs of Staff, the senior military adviser to the president.
General Brown would succeed Gen. Mark A. Milley, whose term has spanned four tumultuous years that encompassed efforts by President Donald J. Trump to use active-duty troops against American protesters; the riots at the Capitol on Jan. 6, 2021; the chaotic withdrawal from Afghanistan; and the war in Ukraine.
General Brown’s confirmation would also mean that along with Defense Secretary Lloyd J. Austin III, the top two Pentagon leaders would be Black men for the first time in history.
The White House said Mr. Biden would announce the nomination in the Rose Garden on Thursday afternoon.
General Brown, who has extensive experience in the Middle East and Asia, would join Mr. Austin in advising Mr. Biden on national security matters from the war in Ukraine to China’s military expansionism in the Asia-Pacific region. A senior administration official who spoke on condition of anonymity said General Brown was deeply knowledgeable about the challenges posed by China and that he had a strong awareness of NATO’s capabilities and perspectives.
The two men would also represent the Pentagon at congressional hearings, before often hostile Republican lawmakers who have complained that the Defense Department has become too “woke.”
For instance, Senator Tommy Tuberville, Republican of Alabama, complained during a radio interview this month that the Biden administration’s efforts to expand diversity in the military were weakening the force. “We are losing in the military, so fast, our readiness in terms of recruitment,” Mr. Tuberville said. “And why? I’ll tell you why. Because the Democrats are attacking our military, saying we need to get out the white extremists, the white nationalists.”
He said that while Democrats consider white nationalists to be racists, “I call them Americans.”
In appointing another African American man to a senior Pentagon position, Mr. Biden may be setting up a contentious period on Capitol Hill. But the president is also recasting the characters in a photograph of Mr. Trump, surrounded by Pentagon leaders who were exclusively white.
General Brown, a fighter pilot, won out over his closest competitor, the Marine Corps commandant, Gen. David H. Berger. Known widely as “CQ,” General Brown is not a talker like General Milley, who loves long historical expositions that connect the modern-day military and political maneuvering of the past. But General Brown brings to the job an ability to meet the moment when it arises.
Take the nationwide protests around the death of George Floyd, an African American man, in June 2020 at the hands of Minneapolis police officers. Mr. Trump wanted to invoke the Insurrection Act to send troops to target the protesters. General Brown was days away from his Senate confirmation vote in a Republican-led Senate to be Air Force chief of staff, but that did not stop him from posting a five-minute video online that electrified the rank and file.
“I’m thinking about how full I am with emotion not just for George Floyd, but the many African Americans that have suffered the same fate as George Floyd,” General Brown said in the video, an unusually public statement by a high-ranking military leader about a sensitive and politically charged issue.
“I’m thinking about protests in my country ’tis of thee, sweet land of liberty, the equality expressed in our Declaration of Independence and the Constitution that I have sworn my adult life to support and defend. I’m thinking about a history of racial issues and my own experiences that didn’t always sing of liberty and equality.”
It was an extraordinary move for a general recently promoted by Mr. Trump, who at the time was angry about what he viewed as Pentagon intransigence over his desire to deploy the troops. But General Brown’s video also instantly identified as a potential heir — should he survive the remaining months of Mr. Trump’s tenure — to General Milley.
Eric Schmitt contributed reporting.
