When you serve as U.S. ambassador to a foreign capital, you represent your country, of course. But you are also the personal representative of the president. Professionalism demands that career foreign service officers — like career military officers — follow the orders and pursue the policies of our elected, civilian leadership.

If you cannot do that, the honorable and right thing to do is resign. That is what I did in July, when I stepped down as U.S. ambassador to Estonia. Now, with my formal departure this week from the U.S. Foreign Service after 33 years, I can more fully explain why.

Service in the diplomatic corps and the military are alike in another key respect. In both worlds, a special burden attaches to any individual in leadership. Within both hierarchies, each of which bears a share of responsibility for conducting U.S. foreign policy, those in leadership roles can — and should — advocate for the policies and strategies they believe in.