Turkey's state-run Anadolu news agency also reported on the ceasefire -- signed by Russia, Turkey and Iran -- saying a joint working group will be set up by the agreement's three guarantor countries to determine the precise borders of the four zones by June 4. Lavrentyev, whose remarks were carried by Russian news agencies, said U.S.-led coalition aircraft would be able to operate against the Islamic State group in specific areas, but the "de-escalation zones" were now closed to their flights. According to Russian official Alexander Lavrentyev, U.S.-led coalition aircraft as well as aircraft from other nations would be able to engage ISIS in other areas:

Lavrentyev, whose remarks were carried by Russian news agencies, said “the operation of aviation in the de-escalation zones, especially of the forces of the international coalition, is absolutely not envisaged, either with notification or without.
Russia, Iran and Turkey reach an agreement, effective this midnight, to establish four "safe zones" in Syria over which all military aircraft, including Turkish, Russian, and American aircraft, will be barred from flying.