Two other vessels were slated to be modernized since at least 2017 as Project 949AM, to extend their service life and increase combat capabilities but it is unclear whether work continues as of 2023.

The Oscar class was designed to attack NATO carrier battle groups using long-range P-700 Granit (SS-N-19 "Shipwreck") anti-ship missiles and targeting data provided by the EORSAT [it] satellite system (via the submarine's "Punch Bowl" antenna).

[8] In September 2015, Russian Defence Minister Sergey Shoygu announced during his visit to Zvezda shipyard, that at least three Oscar-class submarines will undergo repair and modernization to extend their service life by 20 years.

[14] Eleven Project 949A Antey submarines were completed at Severodvinsk, of which five were assigned to the Soviet Northern Fleet.

The Federation of American Scientists[16] reports that this submarine carries an emergency crew escape capsule; it is possible that these doors cover it.

[20][22] However, while carrying smaller unmanned underwater vehicles (UUVs) would be possible as-is on an Oscar-class hull, the accommodation of a midget submarine such as Project 18511 Paltus or the even larger Project 10831 Losharik,[23] would probably require a major hull extension in order to accommodate a docking compartment.

For example, the length of the submarine BS-64 Podmoskovye was increased by 9 metres (30 ft) even though the SLBM missile compartment was completely removed.

[24][25] Belgorod will be reportedly used as a carrier of the rumored Poseidon (NATO reporting name Kanyon) nuclear-powered, thermonuclear armed unmanned underwater device capable to carry a 100 Mt thermonuclear warhead, with at least four such devices being carried horizontally in place of the 24 P-700 Granit (SS-N-19 Shipwreck) launchers for a total yield of 600 megatonnes of TNT.

[22][29] On 23 April 2019, Belgorod was floated out of a slipway during a ceremony at the Sevmash shipyard, watched by the President of Russia Vladimir Putin via a TV-link.

Further work was to be completed afloat and the submarine was scheduled to start its factory and state trials in 2020 after which it was to be delivered to the Russian Navy.