German Chancellor Angela Merkel is honored with an Honorary Doctorate of Laws Degree during the commencement of Harvard University in Cambridge, Massachusetts, on May 30, 2019 | CJ Gunther/EPA-EFE Merkel takes aim at Trump in ‘tear down walls’ speech German chancellor warns Harvard graduates of the dangers of protectionism and ignoring climate change.

Angela Merkel urged Harvard graduates Thursday to “tear down walls of ignorance and narrow-mindedness” in a speech laced with apparent jibes at Donald Trump and his policies.

Though she did not name the U.S. president, the German chancellor devoted much of her Harvard University commencement speech to attacking major pillars of Trump’s presidency: protectionism, trade wars and building walls.

She also warned of the “threat climate change poses to our planet’s resources” and called for the world to work together. Trump announced in 2017 that he would pull the U.S. out of the Paris climate agreement.

The German chancellor began her speech by describing her life in former East Germany before the fall of the Berlin Wall. She said that every day on her way home from her work, she would walk toward the wall, only to have to “turn away from freedom” on the other side at the last minute.

“The Berlin Wall limited my opportunities. It quite literally stood in my way,” Merkel said at Harvard, which earlier in the day awarded her an honorary degree.

“I want to leave this wish with you: Tear down walls of ignorance and narrow-mindedness, for nothing has to stay as it is" — German Chancellor Angela Merkel

She further stressed “multilateralism instead of unilateralism,” a “global” way of thinking rather than a national one, and “being open-minded instead of isolationist.”

“Protectionism and trade conflicts jeopardize free international trade and therefore the very foundations of our prosperity,” Merkel said.

The chancellor received chuckles and applause from the audience when she seemed to comment on Trump’s reputation for impulsiveness, stressing that it’s better not to “always act on our first impulses,” even under pressure.

“Take a moment to stop, be still, think, pause,” she said.

The audience of students, parents, and alumni gave Merkel a standing ovation when she said it is important not to “describe lies as truth, and truth as lies.”

Though most of her speech was in German, she made a point to conclude it in English: “I want to leave this wish with you: Tear down walls of ignorance and narrow-mindedness, for nothing has to stay as it is.”

She added: “Take joint action in the interest of the multilateral, global world. Keep asking yourselves: Am I doing something because it is right, or simply because it’s possible? … Letting go of the old is part of the new beginning. And above all, nothing can be taken for granted. Everything is possible.”

Merkel, who has led Europe's largest economy for more than a decade, announced last year that she would not seek another term as chancellor after her current one ends in 2021. That announcement followed a poor showing for her conservative bloc in the 2017 election as well as reverses in regional elections.

The German chancellor's visit to the U.S. did not include a trip to the White House to see Trump, although she is due to attend a lunch in the U.K. with Prime Minister Theresa May at which the president is also likely to be present.

Trump himself was the commencement speaker on Thursday at the Air Force Academy graduation in Colorado.

Trump used his speech to tout the strength of the American armed forces, telling graduates that they would "redefine warfare at a critical time in American history," and reiterate his mantra of America first.

“No longer will we sacrifice American interests to any foreign power. We don’t do that anymore," he said. "In all things and ways we’re putting America first and it’s about time.”

Merkel followed in the footsteps of a number of other German leaders who have spoken at Harvard's past commencement ceremonies, including the late Cold War leader Helmut Kohl, who spoke in 1990 as West Germany's chancellor, before the country's reunification later that year. Konrad Adenauer — the co-founder of Merkel's Christian Democratic Union and West Germany's first chancellor after World War II — spoke in 1955.

Other prior Harvard commencement speakers include civil rights leader John Lewis last year, Facebook CEO Mark Zuckerberg, Hollywood director Steven Spielberg and entrepreneur Oprah Winfrey.