U.S. Undersecretary of State for Political Affairs retires

The top career U.S. diplomat Tom Shannon announced Thursday he will step down, TIME reports.

The State Department’s third-ranking official, Undersecretary of State for Political Affairs, informed agency staffers that he will retire as soon as a successor for his Senate-confirmed post is chosen and ready to assume the job.

Shannon, who holds the rank of “career ambassador” — the highest in the foreign service — said he was retiring for personal and not political reasons.