Defense Secretary Pete Hegseth addressed reporters at The White House after The Washington Post claimed he ordered a military strike to leave no survivors.
Chollet faces confirmation difficulties, as Republican Sen. Tommy Tuberville has placed holds on Pentagon nominees over the department's abortion policy.
Biden is likely to face questions from NATO allies on why he would send a weapon into Ukraine that more than two-thirds of alliance members have banned.
By Zeke Miller, Tara Copp and Lolita C. Baldor, AP