Two Turkish helicopters and two U.S. choppers took off from Akcakale in Sanliurfa southeastern Turkey, where the two countries' armed forces have a joint operations center.
They flew to the Syrian side of the border.
The countries' armed forces had previously done three joint helicopter flights and a land patrol, Anadolu news agency reported.
On August 7, Turkish and U.S. military officials agreed to set up a safe zone in northern Syria and develop a peace corridor to facilitate the movement of displaced Syrians who want to return home. They also agreed to establish a joint operations center.
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