DAMASCUS -- Russian nighttime cruise missile strikes targeted and destroyed several positions of the Islamic State (IS) militants in three Syrian provinces, the official Syrian news agency SANA reported Wednesday, citing a military source.

The strikes, which were launched from Caspian Sea, destroyed a factory for making explosive devices, weapon depots, fuel storages, and training centers of the IS in the northern provinces of Raqqa, Aleppo and Idlib, said SANA.

The news came as the Russian Defense Ministry released a video footage, showing the cruise missile strikes that were launched from the Caspian Sea overnight against the IS positions in Syria. The missiles flew over Iran and Iraq before slamming their targets in Syria.

The Russian warplanes started on Wednesday their airstrikes against rebel positions in several Syrian areas, marking the first Russian military involvement in the war on terrorist groups in Syria.

Damascus has confirmed that the Russian air raids came upon the request of Syrian President Bashar al-Assad, according to SANA.

Moscow has recently amplified its assistance to the Syrian military forces, and Russian officials promised more of such aid, including specialists, to Damascus.

Russia says the increase in military supplies aims to combat terrorism in accordance with international law.