Russian Defense Minister Sergei Shoigu said Tuesday that the military had launched strikes in Syria for the first time from a submarine stationed in the Mediterranean.

“We used Calibre cruise missiles from the ‘Rostov-on-Don’ submarine from the Mediterranean Sea,” Shoigu told President Vladimir Putin, Russian news agencies reported.

Shoigu added that Russian strikes launched on Tuesday had been aimed at “two terrorist strongholds” around Raqqa, the de facto Syrian capital of the ISIS jihadist group.

In late September, Russia began its bombing campaign in Syria in support of Assad, over a year after an international coalition began its strikes targeting the ISIS group.

Russia is coordinating its air strikes with Damascus, unlike the U.S.-led coalition, whose action has been criticized by Assad and his government as ineffectual. Assad said the Russians had entered the conflict in a “legal way” — with Syria’s permission.

AFP contributed to this report