Russia's Defense Minister says that the military has destroyed a number of oil facilities and tankers controlled by the Islamic State group, cutting its income.

Sergei Shoigu reported to President Vladimir Putin Friday that Russian warplanes have destroyed 15 oil facilities in Syria and 525 trucks carrying oil in bombing this week. He says this deprived IS of $1.5 million in daily income from oil sales.

Shoigu says the strikes also inflicted significant casualties, including more than 600 militants killed in just one strike in the province of Deir el Zour.

According to Shoigu, Russian warplanes flew 522 sorties and destroyed over 800 targets in the last four days. Long-range bombers and navy ships have launched 101 cruise missiles in four days, including 18 fired from the Caspian.