Special to WorldTribune.com

NICOSIA — The Syrian Air Force has conducted one of the most punishing air strikes on Islamic State of Iraq and Levant.

The Syrian Air Force attacked ISIL facilities in the northern city of Raqqa. The Syrian opposition said fighter-jets and helicopters conducted repeated sorties and killed dozens of ISIL fighters.

Opposition sources said the air strikes reflected the strategy of the regime of Syrian President Bashar Assad. They said Assad allowed ISIL to destroy rebel strongholds while preventing the movement from retaining crude oil fields in the northern province of Dir Al Zour.

“The regime carried out 13 raids on the city of Raqqa and 11 on the town of Tabqa in Raqqa province, killing at least 31 militants and wounding dozens of them,” the opposition Syrian Observatory for Human Rights said.

Syrian Observatory said the attacks took place on Aug. 17 and marked the “most intensive” air operations on ISIL. Until June 2014, the Syrian military avoided ISIL as the Al Qaida movement targeted Sunni rebels in northern Syria.

“The regime strikes ISIL where it is strong,” Syrian Observatory director Rami Abdul Rahman said. “In regions where the group is confronted by rebels, it doesn’t intervene so that the two enemies weaken each other.”

The latest air strikes came amid ISIL’s sweep of rebel strongholds in the Aleppo province. The sources said ISIL was moving toward the city of Aleppo, about 20 percent of which remains in rebel hands.

  Aleppo, Assad regime unleashes ‘intensive’ air strikes on ISIL forces in Syria, Assad regime unleashes ‘most intensive’ air operations against ISIL in Syria, Raqqa, Syrian Observatory for Human Rights