Direct proof of use
Russia publicly used Project 636.3 Improved Kilo submarines as submerged Kalibr cruise-missile launch platforms during its intervention on the Syrian government side of the 2011 Syrian Civil War. The first documented strike came on December 8, 2015, when Defence Minister Sergei Shoigu told President Vladimir Putin that the Rostov-on-Don submarine had launched Kalibr missiles from the Mediterranean Sea against targets in Syria.
Subsequent reporting and missile-tracking summaries identify additional Black Sea Fleet Project 636.3 boats in Syrian strikes. In 2017, Krasnodar was reported in Kalibr launches near Palmyra and Hama, while Veliky Novgorod and Kolpino were reported firing Kalibr missiles from submerged positions against targets in Deir ez-Zor, Idlib, Mayadin, and Abu Kamal.
Sources: Kremlin Rostov-on-Don Briefing, Defense News Rostov-on-Don Report, Al Jazeera Palmyra Kalibr Report, CSIS Hama Kalibr Report, CSIS Idlib Kalibr Report, CSIS Mayadin Kalibr Report, CSIS Abu Kamal Kalibr Report
Timeline
The publicly documented Syrian Civil War use pattern begins with Rostov-on-Don in December 2015 and becomes more frequent in 2017 as Russian naval forces in the eastern Mediterranean supported Syrian government operations against Islamic State and other armed groups.
The dated reports distinguish submarine launch platforms from other Russian sea and air launchers: some strikes combined a Project 636.3 submarine with frigates, while others named only submarines or paired submarine fire with Russian bomber operations.
Sources: Defense News Rostov-on-Don Report, CSIS Hama Kalibr Report, CSIS Idlib Kalibr Report, CSIS Mayadin Kalibr Report, CSIS Abu Kamal Kalibr Report
Operational role
In this conflict, Project 636.3 submarines were not documented as coastal-control or anti-submarine platforms in combat; their cited role was long-range land attack from the Mediterranean. Sources consistently describe Kalibr cruise-missile launches against command posts, ammunition depots, equipment concentrations, and other militant or Islamic State targets inside Syria.
The boats operated as part of Russia's wider naval and air campaign in support of the Syrian government. The public record also shows an attribution boundary: Russian official statements and secondary reports name the launch platforms and claimed target categories, but they generally do not provide independent battle-damage verification.
Sources: Jamestown Syria Missile Analysis, RFE/RL Hama Missile Report, CSIS Idlib Kalibr Report, CSIS Mayadin Kalibr Report, CSIS Abu Kamal Kalibr Report