In a statement sent out by the White House, the president urged all Americans to join him in "grateful prayer" for three things.

"First, for our troops and diplomats who carried out this mission of mercy in Kabul and at tremendous risk with such unparalleled results: an airlift that evacuated tens of thousands more people than any imagined possible," he said in the statement. "Second, to the network of volunteers and veterans who helped identify those needing evacuation, guide them to the airport, and provide support along the way. And third, to everyone who is now – and who will – welcome our Afghan allies to their new homes around the world, and in the United States."

He ended his statement with a moment of gratitude for the sacrifice of the 13 service members who were killed in Kabul last week "to save tens of thousands."

The president thanked the military commanders and service members for their execution of the "dangerous retrograde from Afghanistan as scheduled," in a statement released by the White House Monday evening.

"The past 17 days have seen our troops execute the largest airlift in US history, evacuating over 120,000 US citizens, citizens of our allies, and Afghan allies of the United States. They have done it with unmatched courage, professionalism, and resolve. Now, our 20-year military presence in Afghanistan has ended," Biden's statement said.

"Tomorrow afternoon, I will address the American people on my decision not to extend our presence in Afghanistan beyond 8/31," his statement continued. "For now, I will report that it was the unanimous recommendation of the Joint Chiefs and of all of our commanders on the ground to end our airlift mission as planned. Their view was that ending our military mission was the best way to protect the lives of our troops, and secure the prospects of civilian departures for those who want to leave Afghanistan in the weeks and months ahead."

ABC News' Luis Martinez asked Gen. Kenneth McKenzie, the commander of U.S. Central Command, if he thought there may be some people who had false hope that they had more of Aug. 31 to be evacuated -- the last American flight lifted off from Kabul a minute before midnight local time.

"There is a lot of heartbreak associated with this departure," McKenzie said. "We did not get everybody out that we wanted to get out. But I think if we stayed another 10 days, we would not get everybody out that we wanted to get out. And there still would have been people disappointed. It's a tough situation."

"I want to emphasize that simply because we have left, that doesn't mean that the opportunities for both Americans that are in Afghanistan that want to leave and Afghans who want to leave, they will not be denied that opportunity. I think our department of state is going to work that very hard in the days and weeks ahead," he continued.

No American civilians made it out on the final five flights that took off from the Kabul airport, Gen. Kenneth McKenzie, the commander of U.S. Central Command, said.

He said that "the vast majority" of U.S. civilians were able to leave and that the evacuation activity ended about 12 hours before the final American flight took off, he said.

The U.S. had continued to reach out to Americans still there "and were prepared to bring them on," but none made it to the airport, he said.

"We have evacuated more than 6,000 U.S. civilians, which we believe represents the vast majority of those who wanted to leave at this time," McKenzie said.