The head of NATO Wednesday gave a historic speech to Congress that was as much about celebrating the military bloc as it was about U.S. lawmakers signaling their continued commitment to the alliance amid a period of turbulent trans-Atlantic relations.

“Together, we represent 1 billion people,” NATO Secretary General Jens Stoltenberg said of the 29 nations that make up the Western military alliance. “We are half of the world’s economic might and half of the world’s military might. When we stand together, we are stronger than any potential challenger economically, politically, and militarily.”

That line drew a standing ovation, one of many lawmakers gave Stoltenberg, a former prime minister of Norway and the first NATO chief to address a joint session of Congress. The invitation was jointly extended by House Speaker Nancy Pelosi and Senate Majority Leader Mitch McConnell.

President Donald Trump has long been critical of the bloc, publicly chastising NATO members like Germany for what he considers inadequate defense spending.

Watch: Despite Trump’s criticism of NATO, chief gets multiple standing ovations in rare speech to Congress

Stoltenberg was in Washington to celebrate the alliance’s 70th anniversary this week. The occasion was originally conceived as a summit for government heads but was downgraded to a foreign minister-level meeting, which minimizes Trump’s participation. Stoltenberg did meet with Trump on Tuesday at the White House, where the president repeated his criticism that Germany does not pay its “fair share.”

The president’s comments on NATO have repeatedly alarmed many in Europe and Canada, even causing some to question whether the United States would come to their defense if under attack.

“The strength of NATO is that despite our differences, we have always been able to unite around our core values to defend each other, to protect each other and to keep our people safe,” Stoltenberg said.

The NATO chief generally supported Trump’s demands that alliance members spend more on defense. But he appeared to challenge Trump’s insistence that America’s allies take advantage of U.S. economic and military largess.

Stoltenberg’s repeated message to Congress was that the United States is stronger because of its friends and allies.

“We need this collective strength because we will face new threats and we have seen so many times before how difficult it is to predict the future,” Stoltenberg said. “We need a strategy to deal with uncertainty. We have one. That strategy is NATO.”

“It is good to have friends,” he said, concluding his remarks to much whooping and hollering from the gathered lawmakers.

Congress’ enthusiastic backing of NATO comes as domestic public support for the alliance remains one of the most unifying elements of U.S. foreign policy. According to a March Pew survey, 77 percent of Americans believe NATO is good for U.S. interests, with 82 percent of Democrats and 71 percent of Republicans backing the alliance.

The Senate Foreign Relations Committee is expected to advance to the floor Wednesday a resolution upholding the importance of NATO.

“Congress feels strongly that the financial commitment must be met,” Senate Foreign Relations Chairman Jim Risch of Idaho said at a Tuesday hearing, referring to the longstanding goal for each NATO member to spend at least 2 percent of GDP on defense. “I know of at least one other person in this town who feels even more strongly, and I have discussed this with him on a number of occasions. We are all dedicated to the fact that commitments made must be met.”