US Ambassador to Estonia resigns, criticizes Trump over European rhetoric

Another senior American diplomat is leaving the foreign service because of President Donald Trump's policies and rhetoric.

U.S. Ambassador to Estonia James Melville posted on his personal Facebook page Friday to condemn Trump's comments on the European Union and North Atlantic Treaty Organization (NATO) and let friends know he is resigning.

"A Foreign Service Officer's DNA is programmed to support policy and were 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. Having served under six presidents and 11 secretaries of state, I never really thought it would reach that point for me," he wrote, echoing what other senior diplomats have said in their public resignations over the last year and a half.

But it has reached that point, he said, after Trump bashed America's European allies, where Melville has spent the majority of his career.

"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," he wrote.

A State Department spokesperson confirmed to ABC News that Melville "announced his intent to retire" Friday, noting, as Melville does in the post, that he will serve until July 29.

Melville has been in his post for three years, and he had been planning to retire anyway, but because the Trump administration has not nominated anyone to replace him, he could have chosen to stay on.

He acknowledged his decision "takes no courage," especially because he'll get a full pension with his retirement.

But Foreign Policy magazine, which was first to report the news, said that Melville is known as a quiet, disciplined officer, making this public resignation all the more shocking.

Melville has not returned ABC News' request for comment.