NATO said Friday it was naming Gen. Curtis Scaparrotti, commander of U.S. forces in South Korea, to become its top commander in Europe.
Scaparrotti, who replaces US General Philip Breedlove, will have to handle the Atlantic alliance's tense relationship with Russia.
Moscow is leading a bombing campaign in support of President Bashar al-Assad in Syria and allegedly backing rebels in eastern Ukraine against forces of the western-backed government in Kiev.
"The North Atlantic Council approved the nomination of General Curtis M. Scaparrotti, United States Army, to the post of Supreme Allied Commander Europe," NATO said in a statement.
Upon completion of "national confirmation processes," he will succeed Breedlove, a U.S. air force general who has served in the post since May 2013, NATO said.
A European diplomat said the change had been expected in the position which is always held by an American.