Secretary of State John Kerry took a swing at GOP front-runner Donald Trump during a commencement speech to Northeastern University graduates Friday, criticizing Trump’s strategy to build a border wall in an effort to curb illegal immigration and improve upon the security of America.

Kerry told the graduates that a border wall is no contest to the threat of terrorists trying to enter the United States.

Close

“There are no walls big enough to stop people from anywhere, tens of thousands of miles away, who are determined to take their own lives while they target others,” said Kerry.

While Kerry didn’t specify that he was referring to the presumptive Republican nominee, he strongly alluded to Trump, who has been rallying for a wall being built along the southern border of the United States throughout the 2016 campaign.

“So I think that everything that we’ve lived and learn tells us that we will never come out on top if we accept advice from sound-bite salesmen and carnival barkers who pretend the most powerful country on Earth can remain great by looking inward,” said Kerry.

Kerry suggested the advancement of technology had made the need for national borders obsolete. He criticized the idea of “hiding behind walls at a time that technology has made that impossible to do and unwise to even attempt.”

Kerry told graduates to be prepared to enter a world that won’t include Trump’s vision for a border wall.

“The future demands from us something more than a nostalgia for some rose-tinted version of the past that did not really exist in any case,” he said. “You’re about to graduate into a complex and borderless world.”

To read about places where border walls have been successful, click here.