The top US diplomat for Europe is resigning after only 14 months on the job in a blow to Trump administration efforts to maintain trans-Atlantic unity.
The State Department says Wess Mitchell will leave his post in mid-February. He is the assistant secretary of state for Europe and Eurasian affairs.
The department's deputy spokesman Robert Palladino said Mitchell has been a "valued and effective leader" and a "good friend to our allies and partners in Europe".
Mitchell's departure comes at a time of fractious relations between Washington and European capitals amid disagreements over trade, defence spending and the US withdrawal from the Iran nuclear deal.
Mitchell took up the job in October 2017 under former Secretary of State Rex Tillerson after 12 years at a think tank focused on Central European issues.