Speaking to Fox News, the Senator from South Carolina said: "Afghanistan is like a freefall. Al Qaeda is flourishing there, IS (Islamic State) is getting stronger," Khaama Press reported.
He also accused the Taliban of policing Al Qaeda.
Graham called Afghanistan the biggest national security threat in the near term and its humanitarian situation as the largest disaster on the planet which is getting worse.
Terming Joe Biden as "the most incompetent President", the Senator said that his plans on Afghanistan did not work and if there is someone to blame for the looming crisis in the war-torn nation, then "Biden should look in the mirror".
"President Joe Biden turned down military advice. They don't know if there is 350 or 700 American left behind but we do know that there are thousands of Afghans who fought along our side that have been left behind," Graham added.