The Typhoon-class submarines were a class of Soviet-era ballistic missile submarines (SSBNs) that were built in the 1980s and operated by the Russian Navy until the early 2000s.

The Typhoon-class submarines were designed to be the largest and most powerful submarines in the world, with a displacement of over 48,000 tons and a length of over 170 meters.

They were equipped with 20 ballistic missile tubes, each capable of launching R-39N nuclear-tipped missiles.

After the fall of the Soviet Union, the Russian Navy began to retire the Typhoon-class submarines due to their high operating costs, maintenance challenges, and outdated technology.

The last Typhoon-class submarine was decommissioned in 1996.

However, in the early 2000s, the Russian Navy announced plans to re-commission some of the Typhoon-class submarines as part of a program to modernize the country’s submarine fleet.

The plan was to upgrade the submarines with new sensors, communication systems, and weapons, and to extend their service life by 20-30 years.

In 2002, the Russian Navy recommissioned the first Typhoon-class submarine, the TK-208 Dmitri Donskoi, and it began to serve as a testbed for new technologies and systems.

The other Typhoon-class submarines were also upgraded and re-commissioned in subsequent years.

Today, only three Typhoon-class submarines remain in active service with the Russian Navy: the TK-208 Dmitri Donskoi, the TK-12 Arkhangelsk, and the TK-17 Dmitri Pozharsky.

They are used primarily for training and testing new technologies, and are not considered to be part of Russia’s strategic nuclear deterrent fleet.