MOSCOW, March 19. /TASS/. The Project 636.3 diesel-electric submarine Rostov-on-Don that is making an inter-fleet transit after its first planned repairs will join the Russian Navy’s standing taskforce in the Mediterranean Sea, a source in Crimean defense circles told TASS on Friday.

"The submarine Rostov-on-Don will proceed into the eastern Mediterranean in its submerged position after passing Gibraltar. In the Mediterranean Squadron, it will replace the same-type submarine," the source said.

TASS has no official confirmation of this information yet.

As the source said, on Friday when Russia is celebrating Submariner Day, actually all the Black Sea Fleet’s Project 636.3 submarines are on combat watch. As the source noted, the incident when NATO reconnaissance systems ‘lost’ sight of a sub after it passed Gibraltar in its surface position "is hardly worth mentioning." "It is not without reason that NATO has dubbed these submarines ‘black holes,’" the source said.

The Admiralty Shipyard in St. Petersburg in Russia’s northwest has built a series of six Project 636.3 diesel-electric submarines for the Russian Black Sea Fleet. Some of these submarines numerously delivered strikes with Kalibr-PL cruise missiles against terrorist targets in Syria while operating within the Russian Navy’s Mediterranean Squadron.

Russian Navy’s Mediterranean Squadron

The Soviet Navy’s 5th Mediterranean Squadron served as a prototype for the Russian Navy’s permanent Mediterranean taskforce operating at present. The 5th operational Soviet Squadron dealt with the tasks of naval presence in the Mediterranean theater of operations during the Cold War period. Its main rival was the US Navy’s 6th Fleet. The Soviet Squadron was disbanded on December 31, 1992, a year after the disintegration of the Soviet Union.

In 2013, Russia started to create a new operational Mediterranean taskforce. Russia’s new permanent Squadron is dealing with planned and urgent combat missions arising in the Mediterranean theater of operations, including warding off threats to Russia’s national and military security.