After delivering the commencement address and shaking hands with the last of 920 cadets, Biden started to move toward his left to return to his seat, tripped over a black sandbag and fell to his knees. The president was helped up by Air Force officials and Secret Service agents. Biden later pointed to the black sandbag onstage.

The president remained on the stage until the ceremony ended a few minutes later.

Hours earlier, Biden had delivered the commencement address at the ceremony. The president, 80, had been standing on the stage for more than two hours saluting recent graduates as their names were read out, and as the temperature in El Paso County, Colo., was in the 60s.

At the airport for the return flight to Washington, Biden went up the stairs without incident. White House press secretary Karine Jean-Pierre said “he’s totally fine,” adding that the president “boarded with a big smile.”

Upon his return to the White House on Thursday evening, Biden jokingly told reporters that he “got sandbagged,” before skipping once and finishing his walk into the building, according to pool reports.

The president traditionally delivers the commencement address at one of the nation’s military academies. Vice President Harris recently spoke at West Point Military Academy, becoming the first woman to deliver the keynote address there.

Biden used part of his address Thursday to emphasize how far the country’s armed forces have come in terms of racial, ethnic and gender diversity.

“Your class is one of the most diverse classes in the history of this academy — or any academy — to graduate,” Biden said, his voice rising. “That’s why we’re strong. That’s why we are who we are. That’s why we’ll never give up.”

He added that “with every step we’ve taken to harness the full diversity of our nation. … Our armed forces have only grown stronger, more effective and more admired.”

Turning to the global stage, Biden also expressed confidence that Sweden’s bid to join NATO would soon be approved. Finland and Sweden both sought to join the alliance after Russia’s invasion of Ukraine, but NATO member Turkey has so far blocked Sweden’s request, demanding that Stockholm take a tougher approach to Kurdish groups.

But Turkish President Recep Tayyip Erdogan recently won reelection after a hard-fought campaign, and U.S. officials are hopeful he will remove the roadblocks to Sweden’s accession now that he faces less domestic political pressure.

“NATO is more energized and more united than it’s been in decades,” Biden told the Air Force graduates. “It’s now even stronger with the accession of our newest ally, Finland, and soon Sweden, to the alliance as soon as possible. It will happen.”

Biden also took the opportunity to congratulate Air Force Gen. Charles “CQ” Brown Jr., whom he recently nominated to become chairman of the Joint Chiefs of Staff. If confirmed, Brown, a highly seasoned officer, would become the second African American to hold the Pentagon’s top uniformed post.