He's facing ferocious criticism for the chaotic nature of the withdrawal, which included a terrorist attack killing 13 U.S. military and wounding 20 more.
Biden pointed to former President Donald Trump's decision last year to release 5,000 Taliban prisoners and Trump's promise to withdraw by May 1.
"So, we were left with a simple decision: either follow through on the commitment made by the last administration and leave Afghanistan or say we weren't leaving and commit another tens of thousands more troops going back to war," Biden said. "I take responsibility for the decision."
Biden blamed "corruption and malfeasance" for the sudden collapse of the Afghan army that American forces sent hundreds of billions of dollars over 20 years to train and equip.
It's the fate of that advanced, high-tech military equipment that worries some, including Texas Republican Congressman Dan Crenshaw, a former Navy Seal who lost an eye in Afghanistan when an IED exploded.
He fears what the Taliban will do with the huge arsenal they've seized.
"What are they gonna do with it? They're not gonna use it for local security. They're gonna externalize their operations just like our intelligence community believes they will with ISIS and al Qaeda," Crenshaw said. "Again, these people are joined at the hip. They all come from the same tree. So it's not only a disgrace, but it's a direct national security threat."
Republicans demand that President Biden for now focus on bringing home the 100 to 200 American passport holders who still want to depart Afghanistan. The White House press secretary said Tuesday that the State Department does remain in touch with many of those people and will work to get them out of Afghanistan either over land through neighboring countries or by airlift when and if Afghanistan's civilian airports reopen.