Several gunshots were fired at the American Embassy in the Turkish capital of Ankara at around 5am (2am GMT) on Monday morning, although no casualties have been reported.
The assailant fled in a vehicle after between four and five shots were aimed at a security window.
It comes following a deepening diplomatic row between Ankara and Washington regarding the arrest of Pastor Andrew Brunson.
The US threatened to impose further economic sanctions on Turkey if it did not free the evangelical pastor, who is imprisoned in the country on terrorism charges.
US President Donald Trump announced the doubling of tariffs on steel and aluminium imports from Turkey, in protest over the detention of Brunson..
Video credit: Ruptly