The Project 941 Akula heavy missile submarine cruisers (SSBN Typhoon according to NATO codification) are a series of Soviet and Russian nuclear-powered strategic submarines of the third generation. The main armament is 20 R-39 (RSM-52) ballistic missiles. The world's largest submarines. A total of six ships were built, as of 2020, three ships have been scrapped, one (TK-208 Dmitry Donskoy) is in service as an experimental ship, two more - TK-17 and TK-20 are in reserve.