Senate threatens to subpoena Defense Sec. Austin

"A full accounting of the U.S. response to this crisis is not complete without the Pentagon, especially when it comes to understanding the complete collapse of the U.S. trained and funded Afghan military," Menendez said.

U.S. Secretary of State Antony Blinken is testifying before the Senate Foreign Affairs Committee on the U.S. withdrawal from Afghanistan a day after he did the same for the House Foreign Affairs Committee.