ISTANBUL, TURKEY — Snow and low visibility forced Turkey to close the Bosphorus Strait on Jan. 8, according to Bloomberg. No timetable has been given as to when the strait may reopen.

The Bosphorus Strait is a natural strait connecting the Black Sea to the Sea of Marma. It is one of the world’s most strategic waterways and is a key transit point for the export of Russian oil and grain from the Black Sea ports.

According to Bloomberg, the closure of the Bosphorus Strait leads to disruption in the supply of oil from Russia, Kazakhstan and Azerbaijan.