Two Russian submarines - Velikij Novgorod and Kolpino - launched seven Kalibr cruise missiles against ISIS positions south-east of Deir-ez-Zor in Syria, the Russian defense ministry reports. Gen. Igor Konashenkov said that intelligence showed the missiles hit the targets southeast of Deir el-Zour.
Russian Federation has been helping Damascus in the fight against terrorists since September 30, 2015, at President Bashar Assad's request.
The craft were operating in the eastern Mediterranean, news agencies said, and struck targets in the suburbs of Deir Ezzor, in Syria's east.
The country has repeatedly fired salvos of such missiles, from both the sea and mainland Russian Federation.
ISIS, which has suffered significant losses in Syria and Iraq has launched a race for control of the border with Iraq, now still in the militants' hands.
On Thursday, a surviving Hezbollah fighter was returned to Lebanon.
The head of Britain's Syrian Observatory for Human Rights said buses and vehicles carrying about 400 militants and civilians crossed into Deir el-Zour province Wednesday.
Turkey-based activist Omar Abou Layla says local activists reported "fanatical" levels of strikes on three IS-held towns and villages on the Euphrates River valley on Thursday, including an attack on the national hospital in the IS stronghold of al-Mayadeen.
US -backed militias fighting Islamic State are not planning to enter the city of Deir al-Zor in eastern Syria, a USA military spokesman said on Thursday, reducing the chances of the American allies coming face to face with Syrian government forces.