Rebels ejected troops loyal to Syrian president Bashar al-Assad from an air base in the northwest on Wednesday, consolidating their control of the entire Idlib province following a two-year siege.

The province, which borders Turkey and overlooks the coastal heartland of Assad’s Alawite sect, is the second to fall entirely into the hands of rebels who have been fighting the Syrian government for more than four years.

Militants of the self-declared Islamic State took over the Al-Raqqa Governorate in January of last year and made it their capital.

The militants who now control Idlib are affiliated to rival Islamist groups, including the Nusra Front, Al Qaeda’s Syrian affiliate. They seized Idlib’s provincial capital in March and have since deployed suicide bombers to conquer the airfield at Abu al-Duhur.

Sebastian Usher, the BBC’s Arab affairs correspondent, argues that the Nusra-led coalition’s success has come “both from uniting a variety of rebel militias into a single fighting force and a rapprochement of sorts between their main backers, Saudi Arabia, Qatar and Turkey, which has allowed a new flow of cash and weapons.”

The three Sunni states, who back the largely Sunni opposition against Assad’s minority regime, reportedly mended their differences in May in order to hasten the Iranian-backed dictator’s demise and take the winds out of the sails of Islamic State, a group that has recently attracted most jihadist recruits.

To the dismay of Saudi Arabia, Qatar and Turkey previously supported the Muslim Brotherhood in Syria when the same organization challenges the Saudi monarchy. In 2013, the desert kingdom supported a coup by the Egyptian army against the elected Muslim Brotherhood government in that country.

If there is renewed coordination between the three powers, it seems to be paying off.

In July, Assad was forced to admit that his army faced a shortage of men and needed to give up some areas in order to defend others of greater importance.

A month later, troops withdrew from the northwest, bringing the rebels closer to the Nusayriyah Mountains which shield the Alawite provinces from the rest of the country.

The region, which includes the cities of Latakia and Tartus, is the main recruiting ground for Assad’s core praetorian guard units. Situated on the Mediterranean coast, it also provides the regime with a crucial lifeline to the outside world.

The northern Islamist alliance’s successes on the battlefield may also be prompting Russia, Assad’s patron, into action. Various recent reports said Russian officers were meeting with Iranian and Syrian counterparts in Damascus. The New York Times claimed that Russia had sent prefabricated housing units, capable of sheltering as many as 1,000 military personnel, and a portable air traffic control station to Latakia. The moves come on the heels of a visit to Moscow by Major General Qasem Soleimani, the head of Iran’s expeditionary Quds Force which has been fighting on Assad’s side.