Turkey reinforced army units at the Syrian border hours after President Recep Tayyip Erdogan signaled an imminent cross-border operation against U.S.-backed Kurdish militants in Syria.

Turkey sent additional armored vehicles and troops to the border town of Akcakale late Saturday, across from Tal Abyad in Syria, according to state TV television TRT.

Erdogan said earlier in the day that Turkey was ready to start a military operation in northern Syria to claim areas from the Kurdish militant group YPG and may act “as soon as today or tomorrow.”

“We have made our preparations, completed our operation plans,” Erdogan said at an AK Party meeting in Kizilcahamam in Ankara Province. “We have given the necessary orders.” The operation in the east of the Euphrates river in northern Syria will be carried out by land and air, he said.

Erdogan has vowed to create a buffer zone inside Syria by pushing back Kurdish militants and settling Syrian refugees in the country’s north. Turkey suspects that the U.S. is backing Kurdish aspirations for self-rule in Syria and is prepared to use military force to prevent what it perceives as an attempt to redraw the region’s map.

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