"Coalition forces are conducting joint patrols along the northeastern Syria-Turkey border to assess reports from both the SDF and Turkey regarding skirmishes and cross-border fires between their respective security forces," the statement said, referring to U.S.-allied Syrian Democratic Forces.

The purpose is "to discourage escalation and violence between two of our most trusted partners in the fight to defeat" Daesh, the statement said, adding that all parties in the region should remain focused on defeating the terror group.

Forty terrorists were killed at Iraq’s Mt. Sinjar, and another 49 at Syria’s Mt. Karacok in April 25 airstrikes by Turkish forces against the PKK and its Syrian offshoots, PYD and YPG.

The U.S. cooperates with YPG fighters among SDF ranks, which Ankara protests.

The Turkish military said the strikes, of which local governments as well as the U.S. and Russia had been notified, were meant to prevent the PKK from sending terrorists, arms, ammunition, and explosives to Turkey.

Ankara on Wednesday offered condolences to Kurdish Regional Government President Masoud Barzani over the deaths of up to six Peshmerga troops in the airstrikes.

The U.S. expressed concern about the deaths, saying that the operation lacked coordination with the rest of the coalition.