Biden said the United States had "accomplished" its limited original mission of crushing the international militants groups behind the 9/11 attacks and that with every passing year the rationale for staying was "increasingly unclear."
Trump's active role in Republican politics despite losing the 2020 election is unlike other former presidents, who have tended to retreat from the limelight after leaving the White House.
Under the US Constitution, the president nominates people to serve on the Supreme Court and other federal courts for life, and the Senate votes on whether to confirm them.
He also attacked Fauci's ability to throw a baseball, described him as "king of the flip-flops," and said "Birx was a terrible medical advisor, which is why I seldom followed her advice."
Asked if Biden's diplomatic approach to North Korea would include "sitting with President Kim Jong Un" as former President Donald Trump did, White House press secretary Jen Psaki said.
"It has removed a daily blizzard of misinformation from the ecosystem," Muirhead told AFP. "Not being bombarded is helping people's misinformation immune systems to reset themselves and recover."