National Security Advisor Jake Sullivan said Tuesday that a "fair amount" of U.S. weaponry had fallen into the hands of the Taliban since the hard-line Islamic militant group's rapid takeover Afghanistan in recent days.

During a White House press briefing, Sullivan was ask what will happen with the billions of dollars in equipment, including guns, ammunition and helicopters given to the Afghanistan government in the two decades before its collapse.

TOP BIDEN OFFICIAL ADMITS FALL OF AFGHANISTAN 'UNFOLDED AT UNEXPECTED SPEED'

"We don't have a complete picture, obviously, of where every article of defense materials has gone," the Biden adviser answered briefly. "But certainly, a fair amount of it has fallen into the hands of the Taliban, and, obviously, we don’t have a sense that they are going to readily hand it over to us at the airport."

Rep. Mike Waltz, R-Fla., told Fox News in an interview Sunday night that the situation in Afghanistan is worse than it was before the 9/11 terrorist attacks, and that the Taliban now "have access to massive caches of heavy weaponry, artillery, armored vehicles, ammunition," given how rapidly insurgents were able to sweep the country with little resistance by Afghan forces.

Sullivan admitted in an interview Monday that the Taliban takeover of Afghanistan "unfolded at unexpected speed" but defended President Biden's handling of the withdrawal. 

CLICK HERE TO GET THE FOX NEWS APP

"The president did not think it was inevitable that the Taliban were going to take control of Afghanistan," Sullivan said. "He thought the Afghan national security forces could step up and fight because we spent 20 years, tens of billions of dollars, training them, giving them the best equipment, giving them support of U.S. forces for 20 years." 

"When push came to shove, they decided not to step up and fight for their country," Sullivan said, adding that the president was faced with the question of whether U.S. men and women should be "put in the middle of another country’s civil war when their own army won’t fight to defend them?" 

Fox News' Brooke Singman contributed reporting