President Joe Biden on Monday said he "squarely" stands behind his decision to withdraw U.S. forces from Afghanistan after the Taliban wrested control of the country from the U.S.-backed government Sunday.

In a speech delivered from the East Room of the White House, Biden said his national security team has been "closely monitoring" the situation on the ground in Afghanistan. He acknowledged that what the world witnessed in the past few days was the "rapid collapse" of the Afghani government and military to Islamist Taliban militants and blamed Afghanistan leaders for being incapable of or unwilling to fight a civil war on their own.

"Our mission in Afghanistan was never supposed to have been nation-building. It was never supposed to be creating a unified, centralized democracy. Our only vital national interest in Afghanistan remains today what it has always been: preventing a terrorist attack on American homeland," Biden said.

"As president, I am adamant we focus on the threats we face today in 2021, not yesterday's threats," he added.

The president defended his decision to withdraw U.S. troops from Afghanistan, but offered few words about the disastrous way the U.S. withdrawal has unfolded.

"I stand squarely behind my decision," said Biden. "After 20 years, I've learned the hard way that there was never a good time to withdraw U.S. forces."

The president's speech on the situation in Afghanistan was initially unplanned. Biden was spending time away from public view at Camp David when the Taliban took control of Afghanistan on Sunday. He was expected to remain at the presidential retreat but cut his time there short to return to the White House and deliver remarks on the horrific events taking place in Kabul as the U.S. continues evacuation efforts.

The only public image of Biden released during this time was a photo the White House published Sunday showing the president at an empty conference room table holding a video meeting with his national security team.

This morning, the President and Vice President met with their national security team and senior officials to hear u… https://t.co/9uG3nBq2rO

— The White House (@WhiteHouse) 1629052332.0

Biden changed his schedule amid mounting pressure from Democrats and Republicans to address the unfolding catastrophe in Afghanistan. The president was hammered by both sides for being silent as the U.S. failed to fully evacuate thousands of Afghani interpreters and others who had assisted U.S. personnel for decades during the war against the Taliban.

"Why is Joe Biden hiding?" Sen. Tom Cotton (R-Ark.) asked Sunday. "He should immediately address the nation and answer for the catastrophic situation in Afghanistan. Conference calls between cabinet secretaries and senators don't cut it in a crisis."

"There's no way to hide it. The situation in Afghanistan is another shame on this admin," Rep. Vicente Gonzalez (D-Texas) said. "Withdrawal was never going to be easy but it didn't need to come to this. The US must do everything in its power to help our partners & allies to safety & protect our national security."

White House officials have publicly admitted that the administration was caught off-guard by the speed with which the Taliban seized control of Kabul after U.S. forces began withdrawing on Biden's orders. A U.S. intelligence report leaked to Reuters last week estimated that the Taliban could capture Kabul within 90 days. But by Sunday, Taliban soldiers seized the presidential palace and overthrew the Western-backed government. Afghanistan President Ashraf Ghani was forced to flee the country.

The Afghanistan military, which received decades of training from U.S. forces, collapsed "more quickly than we anticipated," Secretary of State Antony Blinken told CNN Sunday.

National security adviser Jake Sullivan echoed Blinken's comments on Monday, telling NBC's "Today," "It's certainly the case that the speed with which cities fell was much greater than anyone anticipated, including the Afghans, including many of the analysts" watching the situation.

In response, the Biden administration ordered a total of 6,000 U.S. troops to return to Afghanistan to secure evacuation and withdrawal efforts from incursions by Taliban militants. Gen. Frank McKenzie, the commander of U.S. Central Command, met face to face with Taliban leaders Sunday in Doha, Qatar, to inform them that interference with U.S. evacuation efforts at the airport in Kabul would be met with force.

Desperate Afghani citizens have swarmed the Hamid Karzai International Airport seeking to board U.S. military flights and flee the country. Horrific videos posted to social media show the airport in utter chaos, with people clinging to departing U.S. aircraft and falling to their deaths after the planes took off.

The chaos forced U.S. troops to temporarily suspend evacuation efforts and fire warning shots to dissuade the crowd from surging at departing flights. Witnesses told Reuters that at least five people were killed at the airport as hundreds tried to force themselves onto U.S. aircraft. A U.S. official said said the military fired shots into the air in an attempt to scatter the crowd. It's unclear whether the victims died by gunfire or by stampede.

Several former Obama administration officials have come forward to publicly criticize Biden's handling of the withdrawal from Afghanistan. Former U.S. Ambassador to Afghanistan Ryan Crocker said Sunday the Biden's administration had "a total lack of coordinated, post-withdrawal planning" and called the deteriorating situation a "self-inflicted wound."

David Petraeus, who served as CIA director under President Obama, said in an interview that the Taliban's conquest of Afghanistan was "disastrous" and "catastrophic" for the world.

"This is an enormous national security setback and it is on the verge of getting much worse unless we decide to take really significant action," he warned.

Biden on Monday insisted that his national security team was "clear-eyed about the risks" of leaving Afghanistan, which included the possibility that the Taliban would overrun the Western-backed government, but he argued that continued U.S. military presence in the country wouldn't have made a difference since the government in Afghanistan couldn't stand on its own.

"Afghanistan's political leaders gave up and fled the country. The Afghan military collapsed, sometimes without trying to fight," Biden said.

Biden blames Afghans for current crisis: "I know there are concerns about why we did not begin evacuating Afghan ci… https://t.co/SA2He1ArR4

— Tom Elliott (@tomselliott) 1629145265.0

"If anything, the developments of the past week reinforced that ending U.S. military involvement in Afghanistan now was the right decision. American troops cannot and should not be fighting in a war and dying in a war that Afghan forces are not willing to fight for themselves," he added.

"We gave them every tool they could need. We paid their salaries," Biden continued. "We gave them every chance to determine their own future. We could not provide them the will to fight for that future."

The president also laid blame on his predecessor, President Donald Trump, for negotiating a deal with the Taliban to withdraw U.S. forces from Afghanistan in the first place. He said the choice he faced was to follow through with withdrawal or escalate the conflict in Afghanistan by sending thousands of U.S. troops into the nation's third decade of war.

"American troops cannot and should not be fighting in a war and dying in a war that Afghan forces are not willing to fight for themselves," Biden declared.

Addressing his critics, he asked, "How many more generations of America's daughters and sons would you have me send to fight Afghanistan's civil war when Afghan troops will not?"

Concluding, Biden accepted "my share of responsibility" for what is happening in Afghanistan.

"I am president of the United States of America, and the buck stops with me," he said.

"I'm deeply saddened by the facts we now face, but I do not regret my decision to end America's war fighting in Afghanistan," the president added. "I cannot and will not ask our troops to fight on endlessly in another country's civil war."

After delivering his speech, Biden exited the East Room without taking questions from reporters. The White House announced that he will return to Camp David.