President Biden made a forceful case for global alliances on Thursday, telling graduates at the Air Force Academy that rebuilding partnerships with like-minded nations had been the key to asserting American power abroad against adversaries like Russia and China.

“Our partnerships amplify our strength and make us more effective,” Mr. Biden told the academy’s class of 2023 during a sunny, morning ceremony at the Colorado Springs university. “And don’t think our adversaries don’t understand it. They work so damn hard to try to split us.”

Mr. Biden’s commencement address was the third military academy graduation he has addressed since becoming president; he spoke at the Coast Guard ceremony in 2021 and at the Naval Academy in 2022. He addressed West Point graduates twice as vice president.

Mr. Biden, who spent nearly two hours handing out diplomas to the graduates, tripped over a sandbox and fell to the floor on the stage toward the end of the ceremony. He was helped up by Air Force officials and members of the Secret Service.

White House officials later said that he was “totally fine.”

During his remarks, Mr. Biden told the graduates — who will now become second lieutenants in either the U.S. Air Force or the U.S. Space Force — that they bear the burden of helping to safeguard a nation’s way of life.

He said the mission they served was “greater than any person or president” and was part of the reason people around the world respected and admired America.

“It’s our Constitution,” he said. “It’s our country. And it’s our enduring American values.”

He praised the graduates for persevering through four difficult years, including the pandemic that forced them to stay at home during part of their early days at the academy. Despite that obstacle, he declared them ready for leadership in the armed forces.

“You are the very embodiment of American military excellence,” he said. “You are ready for anything — anything. And as I look out today, I give you my word as a Biden, I’ve never been more optimistic, never been more optimistic about the future of this country, in no small part because of you.”

But the president grew most animated when he discussed what he called “one of the greatest assets you will harness throughout your careers.”

“It’s our unmatched network of alliances and partners,” he said.

Mr. Biden did not mention former President Donald J. Trump. But he appeared to refer to his predecessor by repeating his assertion that relationships with foreign capitals around the world were in need of rebuilding when he came into office in 2021.

The president said those partnerships had been crucial in supporting Ukraine in its war with Russia, which has now gone on for more than a year.

“Freedom, sovereignty, democracy, simple dignity,” Mr. Biden said. “Working with a coalition of more than 50 nations, we have delivered historic security assistance that has enabled Ukraine to defend itself.”

Mr. Biden entered office with decades of foreign policy experience, having served for years on the Senate Foreign Relations Committee and for eight years as vice president. He has long emphasized the need for effective alliances as a means for assuring global peace and stability.

In his speech on Thursday, the president made the case that the military strength of the United States was enhanced by the efforts to work collectively to confront challenges to freedom and democracy.

In particular, Mr. Biden said cooperation with allies had aided the United States in confronting China’s economic and military aggression; North Korea’s pursuit of nuclear weapons; and other challenges to stability around the world.

“The United States does not seek conflict or confrontation with China,” he said. “China and the United States should be able to work together where we can solve some global challenges like climate, but we are prepared for vigorous competition. We will stand — stand up for our interest, our friends, for our values.”

Mr. Biden also had some lighthearted moments during his remarks.

He noted that the Air Force Academy was 7,258 feet above sea level and “far, far above that of West Point or Annapolis.” He then joked that he made the comments to ensure that his Air Force One pilots (graduates of the academy) “are willing to take me back to D.C.”

He also followed the tradition of former commanders in chief and waived any minor infractions on the graduates’ school records, part of a tradition at academy commencement ceremonies.

Mr. Biden noted that he had “found myself in a little bit of trouble a couple of times” during his time as a student at the University of Delaware.

“I wish,” he said wistfully, “that my commencement speaker had that power.”