“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. Having served under six presidents and 11 secretaries of state, I never really thought it would reach that point for me,” he wrote in the post, which was obtained by Foreign Policy.

“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, citing Trump’s reported comments in recent weeks that have unnerved U.S. allies.

The post surprised several State Department officials who worked with Melville, describing him as a consummate professional who never let domestic politics impact his job.