Syrian President Bashar al-Assad said Sunday that his coalition with Russia, Iran and Iraq must succeed in Syria’s war, suggesting the alternative would be a region in chaos.

The alliance “must succeed, otherwise we are facing the destruction of the entire region and not just one or two states,” Mr. Assad said in the Islamic Republic of Iran News Network interview.

It was his first public comment since Moscow began airstrikes in Syria in support of his regime last week. Mr. Assad praised Russia, saying it had the vision and fortitude to defeat rebel forces seeking to topple him.

The Syrian president said Russia and his country had a long-standing relationship.

Unlike the West, the Russians “have never tried to impose anything on us throughout the history of this relation, particularly during this crisis,” he said.

Mr. Assad used the interview to blast the U.S.-led coalition that has been fighting Islamic State by air in Syria and Iraq since last fall, saying it had been ineffective in fighting terrorism.

Meanwhile, Russian military officials said its air force was stepping up strikes against targets in Syria, as warplanes carried out dozens more sorties during the weekend, again hitting areas controlled by other opponents of Mr. Assad’s regime as well as Islamic State.