The U.S. ambassador to Panama, John Feeley, announced his resignation. He says he no longer can serve under President Donald Trump.

In his announcement, Feeley said, “As a junior foreign service officer, I signed an oath to serve faithfully the president and his administration in an apolitical fashion, even when I might not agree with certain policies. My instructors made clear that if I believed I could not do that, I would be honor bound to resign. That time has come.”

Feeley swore his oath on July 20, 1990, along with forty-four other members of the 52nd junior officer orientation class, including me.

For nine weeks, we had studied together the rudiments of what a Foreign Service Officer does—from leading staff to dealing with foreign governments, from writing to speaking.

We had gone on retreats together and been advised by our seasoned Foreign Service elders. We had met after classes for happy hours and sometimes played ball on the grassy slope below the Washington Monument.

We knew as we took that oath that we would never again all be in the same place together. On flag day, we had received our assignments to our first posts.

Though some would receive more specialized training, we would soon scatter to South America and Asia and points in between. The typical officer spends two-thirds of his or her career in foreign assignments.

John Feeley, a former Marine Corps helicopter pilot, was more experienced than most of us. Married and a father, he was the kind of person you would want on your side in a crisis, somebody you would trust to lead. We were not surprised as Feeley advanced through the ranks, finally becoming a career ambassador.

Now all that expertise is lost.