Three U.S. ambassadors have now stepped down from their diplomatic posts this year, specifically due to opposition to President Donald Trump and his policies. The latest to do so is James D. Melville Jr., the ambassador to Estonia, who announced in a Facebook post that he will be leaving his job on July 29. After 33 years of public service, Melville decided he could no longer stay on in his role following comments Trump made on Wednesday about the European Union and NATO.

“For the president to say the EU was ’set up to take advantage of the United States, to attack our piggy bank,’ or that ‘NATO is as bad as NAFTA,’ is not only factually wrong but proves to me that it’s time to go,” Melville wrote. Foreign Policy was the first to report Melville’s resignation and the Washington Post later published the full text of his Facebook message. Estonian news outlet Eesti Ekspress also posted a screenshot of Melville’s Facebook message.

Pres. Trump: "We love the countries of the European Union. But the European Union, of course, was set up to take advantage of the United States." https://t.co/WY5hUuaonz pic.twitter.com/KI2nyWTymU — ABC News (@ABC) June 28, 2018

“A Foreign Service Officer’s DNA is programmed to support policy and we’re schooled right from the start, that if there ever comes a point where one can no longer do so, particularly if one is in a position of leadership, the honorable course is to resign,” Melville wrote. “Having served under six presidents and 11 secretaries of state, I never really thought it would reach that point for me.”

Melville wrote that he had “always been very proud of the U.S. role in the aftermath of World War II, of rebuilding a Europe that ideally would be ‘whole, free and at peace’.” The outgoing ambassador insisted he was no hero: “It takes no courage on my part to do so and I can’t hold a candle to my friends who have honorably resigned without the benefit of the full pension I have waiting for me.”

The State Department confirmed that Melville would be retiring. “The United States’ Ambassador to Estonia, Jim Melville, announced his intent to retire from the Foreign Service effective July 29 after 33 years of public service,” a State Department spokesperson said.

Melville is now the third ambassador to step down this year. First came John Feeley, who stepped down as ambassador to Panama in March after announcing his intent to do so in December. Then Roberta Jacobson stepped down as ambassador to Mexico in May.

“I resigned because the traditional core values of the United States, as manifested in the president’s National Security Strategy and his foreign policies, have been warped and betrayed,” Feeley wrote in an op-ed for the Washington Post in March. “I could no longer represent him personally and remain faithful to my beliefs about what makes America truly great.”