Turkey has summoned Russia's ambassador to Ankara over images of a Russian serviceman apparently holding a missile launcher as his ship passed through Turkish waters.
Ambassador Andrei Karlov was summoned to the Foreign Ministry on December 7 over the images published by the Turkish media the day before.
The pictures showed the serviceman resting the launcher on his shoulder while on deck as the ship Caesar Kunikov passed through the Bosphorus Strait.
Foreign Minister Mevlut Cavusoglu called the incident a "provocation."
Under a 1923 treaty, Turkey must let all ships pass through the Bosphorus Strait, which runs through Istanbul, during peacetime.
Russia-Turkey relations have deteriorated sharply since Ankara shot down a Russian fighter jet it said had violated its airspace. A Russian pilot was killed, sparking economic sanctions from the Kremlin.