Turkey’s President Recep Tayyip Erdogan has threatened to close two strategic military bases used by the United States in Turkey, after Washington warned of sanctions over Ankara buying Russian arms.

“If necessary, we can close Incirlik and we can close Kurecik,” Erdogan said on television channel.

The two bases sit on Turkey´s southwest coast, near the border with Syria.

Tayyip Erdogan has regularly raised this possibility in the past, as times of tension between the two countries.

The US airforce uses the airbase at Incirlik for raids on positions held by the armed group in Syria. The Kurecik base houses a major NATO radar station.

Foreign Minister Mevlut Cavusoglu raised the issue of the bases last week.

Responding to the US threat of fresh sanctions, he warned that their closure could be “put on the table”.

Turkey faces US sanctions over its decision to buy the Russian S-400 missile defence system, despite warnings from Washington.

Turkey on Friday had summoned the US ambassador after the US Senate followed the lower house and voted to recognize the 1915 killings of Armenians as genocide. The bill has yet to be signed by President Donald Trump.

Armenia claims 1.5 million died in the killings. Turkey says the number of deaths was far lower and Turks also died, blaming the killings on the First World War.

Turkey objects to the presentation of the incidents as “genocide” but describes the events as a tragedy in which both sides suffered casualties.

Ankara has repeatedly proposed the creation of a joint commission of historians from Turkey and Armenia plus international experts to examine the issue.

Recognition of the 1915 events as “genocide” had for decades stalled in the Congress, stymied by concerns about relations with Turkey.

Turkey and the U.S. are currently experiencing rocky relations over a range of issues, including the latter’s support for the YPG terror group in northern Syria, inaction against the Gülenist Terror Group (FETÖ) as well as anti-Turkey legislation.