The video, taken in the coastal city of Sinop, showed a narrow column of smoke headed high into the blue sky.
In recent days Turkey had issued notices restricting air space and waters off the coastal area to allow firing tests.
A U.S. official, speaking on the condition of anonymity, said that Turkey had tested the S-400 system on Friday but did not provide details. Tests of the S-400s, if verified, could stoke tensions between Turkey and the United States, which sharply opposed Ankara’s purchase of the weapons from Moscow on grounds they compromise shared NATO defence systems.
State Department spokeswoman Morgan Ortagus said the United States has expressed to the most senior levels of the Turkish government that the acquisition of Russian military systems such as the S-400 is unacceptable, adding that Washington has been clear on its expectation that the system should not be operationalized.
