The fighter regiment is planned to fully replace the Su-27SM with its 4++ generation successor, the Su-35S, in the framework of Russia's military modernization program.

Two of Russia’s multirole Su-35S fighter jets have entered into service in the Primorsky Territory in the Eastern Military District, the Pacific Fleet said Friday.

"Pilots have retrained for new combat aircraft…After the pilots’ report to the commander of the fighter regiment completing the task, a ceremony to receive the new equipment was held directly on the airfield," the fleet said in a statement.

The fighter regiment is planned to fully replace the Su-27SM with its 4++ generation successor, the Su-35S, classified by the North Atlantic Treaty Organization (NATO) as Flanker-E.

The air regiment in the Primorsky Territory received its first batch of Su-30M2s Flanker-H air superiority fighters in late 2014, and three advanced MiG-31BM Foxhound interceptors by the end of 2015.

Russia is undergoing a large-scale program to modernize its military hardware by 2020.