The longest-serving U.S. diplomat on Friday delivered a firm rebuke of isolationism in his retirement speech, calling for the country to continue its longstanding push for an “open, rules-based world."

Without directly mentioning or criticizing President Trump, Ambassador Dan Fried rebuffed calls for protectionism and nationalism during his retirement speech. The U.S., he said, has sustained an extended period of relative peace through international institutions and openness.

“This track record suggests that an open, rules-based world, with a united West at its core, is an asset and great achievement, and a foundation for more,” Fried said, according to Reuters.

ADVERTISEMENT

His remarks were an indirect rebuke of Trump’s calls for “America first” policies and his suggestions that the U.S. should reevaluate its relationships abroad.

“Some argue that [an open, rules-based world] is actually a liability, that values are a luxury, that in a Hobbesian or Darwinian world we should simply take our share, the largest possible,” said Fried, who has spent 40 years at State Department and most recently served as Coordinator for Sanctions Policy.

He blasted the idea of “spheres of influence,” in which certain powerful countries hold a certain degree of leverage over other states in their regions, saying that such a notion would allow certain countries, like Russia and China, to “dominate their neighbors through force and fear.”

Fried also warned against an increasingly aggressive Russia, accusing the Kremlin of trying to undo the progress made since the end of the Cold War.

"This great achievement is now under assault by Russia," he said. "It is for the present generation to defend and, when the time comes again, extend freedom in Europe."

Trump has spoken fondly of Russian President Vladimir Putin, at one point calling him a stronger leader than former President Obama. He was also expressed a greater willingness to work with Moscow on issues such as fighting the Islamic State.

But his administration has also been roiled by questions about the president’s and his associates’ ties to Russia. The U.S. intelligence community concluded in December that the Kremlin interfered in the presidential election in favor of Trump.

Since taking office, Trump’s first National Security Adviser Michael Flynn resigned from his post amid revelations that he discussed sanctions with a Russia diplomat, and news reports have surfaced that some Trump associates communicated with Russian officials throughout his presidential bid.