Retired Gen. Lloyd Austin is Biden's nominee for Secretary of Defense; he would be the first Black person to lead the Pentagon if confirmed. President-elect Joe Biden will nominate Austin, a four-star general, to lead the Pentagon, according to the Associated Press. Like President Donald Trump's first defense secretary, James Mattis, Austin will require a congressional waiver to serve, as he is a recent military retiree. Federal law requires seven years of retirement from active duty before taking on the position. Ref. USAToday.