President Recep Tayyip Erdogan said Turkey might send troops to Libya to counter Russian-backed militia forces. The battle for control of Libya threatened to escalate further this week as Turkey said it might intervene to stop the Russian-backed forces now closing in on Tripoli, the capital.

Turkey’s foreign minister suggested Wednesday that the United States could be barred from using two strategic air bases in retaliation to possible U.S. sanctions against his country, the state-run Anadolu Agency reported.

Russia, Turkey and Iran are concerned about the increased presence of terrorist groups in Syria’s Idlib province, the three countries said after talks in Kazakhstan, pledging to coordinate actions aimed at eliminating the militants.