Four Saudi F-15 Eagle jet fighters that Riyadh said it was sending to Turkey will arrive Friday at Incirlik, the Turkish air base near the border with Syria that is becoming the main staging post for the international air war against the Islamic State (ISIS).

CNN Turk reported that two Saudi C-130 military transports arrived at Incirlik, in Turkey’s Adana province, on Tuesday with 30 Saudi Air Force servicemen who will prepare for the arrival of jet fighters.

Turkey’s Foreign Minister Mevlut Cavusoglu said on Thursday that the jets will arrive “today or tomorrow.”

This will be the first time that Saudi aircraft will have been sent to Turkey for potential military operations. They will reportedly take part in counter-Islamic State (ISIS) operations in neighboring Syria.

After they arrive five foreign countries that are part of the US-led coalition against ISIS will have military aircraft operating from Incirlik.

Turkey’s main opposition parties have criticized the government for allowing more and more countries the use of Incirlik in the air war against ISIS.

The Royal Saudi Air Force may deploy 8x F-15S Strike Eagles to Incirlik Air Base in Turkey next week