Forces from the regime of Syrian President Bashar Assad have been able to break the Islamic State (ISIS/ISIL/IS) siege of a key military airbase in the northern province of Aleppo, handing ISIS one of its worst defeats to date.

“Syrian troops, backed by pro-government militia, broke through the Islamic State in Iraq and Syria (ISIS) group’s siege of the Kweyris military airport in northern Aleppo province,” an AFP photographer said.

The video from Syrian state television below shows Syrian Army troops entering the airbase:

The report notes that Russian planes have been carrying out airstrikes in the area, coupled with a notable increase in the tempo of Syrian Army operations. This will doubtless reinforce the narrative that Russian air power is helping the Syrian army turn the tide in the years-long civil war. The recapture of Kweyris is being widely described as the Assad regime’s most significant success of the war.

“The assault comes a week after the Syrian army battled Islamic State to regain control of a road southeast of Aleppo and took back control of the government’s only supply route into the city,” Reuters reports. “Areas around Aleppo have seen weeks of heavy fighting after Syrian troops, backed by Lebanese and Iranian fighters, launched an offensive to retake surrounding territory from rebels and jihadist fighters.”

The Syrian Arab News Agency quotes regime military spokesmen boasting of “concentrated strikes on the hotbeds of terrorists” in Aleppo, and claiming that several notable insurgent commanders have been killed. The Syrian Army also says it has seized a considerable amount of arms and ammunition from defeated ISIS and al-Qaeda forces.

“We are inside the air base. We have met our friends, and the situation is good,” declared a Syrian soldier who took part in the offensive, according to the Associated Press.

Another Syrian officer said, “With the liberation of Kweyris, we will liberate other areas.”

Roughly a thousand troops have been pinned down inside the air base since 2013, repelling multiple attacks from ISIS, which in turn defeated other militant groups to take control of the area. The AP speculates that Syrian troops held firm because they knew they would face terrible fates if captured by ISIS.

Rebel forces have counterattacked, while Syrian troops pushed forward with Russian air cover, launching several deadly artillery attacks described by the Associated Press. This included a shelling of the Tishreen University area that left the street littered with burning cars and blood, as well as artillery strikes against the capital city of Damascus. Some of these attacks are reportedly the work of the Nusra Front, al-Qaeda’s outfit in Syria.