BREAKING: Biden defends Afghanistan withdrawal in wake of 12 service members killed in Kabul

The suicide bombs, for which ISIS-K has taken responsibility, threw the evacuation mission into turmoil as neither Americans nor Afghan allies could travel safely to the airport. It has been reported that more than 1,000 Americans remain in Afghanistan.

"Tough day," Biden began, before describing the events in Kabul, saying that the bombings were carried out by ISIS-K. "I've been engaged all day," he said, "in constant contact" with military commanders in the US, Kabul, and Doha, Qatar.

"The situation on the ground is still evolving, and I'm constantly being updated." He called the servicemen who were killed "heroes," saying that "more than 100,000 American citizens, American partners, Afghans who helped us, others taken to safety, in the last 7 days."

Biden praised the military and their efforts, calling them "the backbone of America," and "the best the country has to offer."

The President expressed his sadness as to the lives lost, saying that "we are outraged as well as heartbroken." He spoke about his son Beau Biden, and his military experience, as well as the physical fall out from that.

Biden repeated his understanding of grief "as a black hole," and expressed his empathy.

"We have a continued obligation, a sacred obligation," he said, to the families of those heroes.

He said "we will not forgive, we will not forget, we will hunt you down and make you pay. I will defend our interests and our people with every measure at my command," he said.

Biden spoke about the attacks planned by ISIS-K, saying that "this mission was extraordinarily dangerous, and why I've been so determined to limit the duration of this mission." Biden said he has been in "constant contact" with military leaders. He noted that many of those in ISIS-K were released from prison by the Taliban.

"We can and we must complete this mission," he said, stating that "we will not be deterred by terrorists, we will not let them stop our mission" and that "we will continue the evacuation."

His message to those who carried out the attack is that commanders have been ordered to come up with plans as to how to "strike ISIS-K assets, leadership and facilities. We will respond with force and precision at our time, at the place we choose, and the moment of our choosing."

"Here's what you need to know, these ISIS terrorists will not win, we will rescue the Americans, we will get the Afghan allies out," he said, "America will not be intimidated."

He said that "we have to remain steadfast," and that "we will complete our mission, we will continue after our troops are withdrawn, to find means by which we can find any American who wishes to get out of Afghanistan. We will find them and we will get them out."

Biden asked for a moment of silence for the fallen before taking questions, saying that the first person he was "instructed to call on was Kelly O'Donnell of NBC."

She asked if leaving Afghanistan was still in the best interests of the United States, given the current situation, and that Americans may be left behind, or if there would be additional forces required to "carry out the evacuation operation."

"I've instructed the US military, whatever they need, if they need additional force, I will grant it. But the military, from the Chairman of the Joint Chiefs, commanders in the field, have all contacted me one way or another, usually by letter, saying they subscribe to the mission as behind, to get as many people out as we can within the timeframe which is allotted," he said.

"With regard to finding, tracking down, the ISIS leaders who ordered this, we have some reason to believe we know who they are, not certain, and we will find ways of our choosing, without large military operations, to get them… wherever they are."

He called on Reuters, who spoke to the criticism of many, including Democrats, of the administration's "dependence on the Taliban to secure the perimeter of the airport. Do you think a mistake was made in that regard?"

"No," Biden said. "I don't." He praised General McKenzie, and said that "we inherited a situation," noting that the Afghan military "collapsed in 11 days." He said it's in the Taliban's interest that "we are able to leave on time."

"The major things we've asked them, moving back the perimeter… stopping vehicles from coming through, searching people who are coming through, it is not what you'd call a tightly commanded regimented operation… but they're acting in their interest," Biden said.

He said that he has no evidence that there's been any "collusion between the Taliban and ISIS in carrying out what happened today" or on those attacks that are "expected to continue" by the administration to continue.

Biden said that "what America says matters," as regards why the US should leave on deadline. He noted that there are additional people who need to be evacuated.

Fox News' Peter Doocy, who seemed surprised to be called on, asked "Mr. President, there had not been a US service member killed in combat in Afghanistan since February of 2020. You set a deadline, you pulled troops out, you sent troops back in, and now 12 Marines are dead. You said 'the buck stops' with you. Do you bear any responsibility for the way that things have unfolded in the past two weeks?"

"I bear responsibility for fundamentally all that's happened of late. But here's the deal—you know, I with you one day would say these things, you know as well as I do that the former president made a deal with the Taliban that he would get all American forces out of Afghanistan by May 1. In return, the commitment was made, and that was a year before, in return he was given the commitment, the Taliban would continue to attack others but would not attack any American forces. You remember that?" He asked Doocy.