The U.S. ambassador to Kenya has unexpectedly resigned, citing tension with superiors in Washington.

Scott Gration released a statement Friday announcing he had submitted his resignation to the Obama administration, to be effective July 28th.

In the statement, Gration said his decision stemmed from “differences with Washington regarding my leadership style and certain priorities.” He did not elaborate.

Some Kenyans criticized the U.S. embassy in Nairobi this week when it hosted a gay pride event. But Katya Thomas, the embassy's information officer, denied there was any link to that event.

“Ambassador Gration's resignation has nothing to do with that event or with our advocacy of LGBT rights.”

Thomas said Gration will probably talk more about his decision at another time.

Gration has served as ambassador to Kenya for a little more than 14 months, after spending two years as U.S. President Barack Obama's special envoy to Sudan.

The diplomat said being ambassador to Kenya was a “dream job” for him and his wife Judy. Gration spent part of his childhood in Kenya, and served a two-year assignment in the country during a long career with the U.S. Air Force.