On Sunday, Turkish President Recep Tayyip Erdogan threatened to close two American strategic military bases in Turkey after Washington warned of sanctions over Ankara's purchase of Russian weapons.
"If necessary, we can close the Incirlik and Kurecik bases," Erdogan said on the pro-government Television Channel A Haber. The bases are located on the southwest coast of Turkey, near the border with Syria.
Erdogan has regularly allowed such a possibility at times of tension between the Us and Turkey in the past.
The U.S. Air Force is using Incirlik Air Base to attack Islamic State positions in Syria. A large NATO radar station is located at the Kurecik base.
Turkish Foreign Minister Mevlut Cavusoglu raised the issue of bases last week. Responding to the threat of new U.S. sanctions, he warned that closing them could be "discussed."
The U.S. threatens to impose sanctions against Turkey over its decision to purchase Russian S-400 surface-to-air missile systems, despite Washington's warnings.
On Friday, Turkey summoned the U.S. ambassador after the U.S. Senate followed the house of Representatives lead and voted to recognize the 1915 Armenian massacres as genocide. The bill has not yet been signed by President Donald Trump.
Armenia claims that one and a half million people died as a result of the killings. Turkey insists that the death toll was much lower and blames the horrors of World War I for the killings, noting that the dead were also among the Turks.