The Russian Defence Ministry announced on November 9th the development of the S-550 air defence system, which state media outlets implied could be related to the S-500 as pictures of the older system were published with the announcement. The statement indicated that during meetings in Sochi from 1-3 November Russian President Vladimir Putin "made a special emphasis on the importance of the advanced development of domestic air defence-missile defence systems, and deliveries of the S-350, S-500, S-550 to the Armed Forces." Further details about the new system were not given. The first pictures of the S-500 were unveiled in July following a test launch at the Kapustin Yar test range targeting a mock ballistic missile, and the long-delayed missile system is expected to enter service before January 2022. Serial production of the system began in August, and the S-500 will be capable of engaging both high value aircraft such as heavy bombers and AEW jets, as well as intercontinental range ballistic missiles and satellites. 

The only air defence system with a similar designation to the S-500 is the new medium ranged S-350, which was designed to protect long range missile batteries such as the S-400 as part of a wider network. Although long range systems such as the S-500 and S-400 are highly versatile, they remain vulnerable to suppression if not properly protected by complementary shorter ranged systems including medium range and point defence platforms. Although the S-550 being a next generation successor to the S-350 remains possible, it may also be a planned replacement for the S-400 which has been in service since 2007 at the latest, and according o some reports as early as 2005, and which may be coming near the end of its production run. The designation S-550 could potentially refer to an export variant of the S-500 or an export-oriented design based on many of the same technologies, if not for the fact that President Putin stressed deliveries of the system to Russia's own armed forces. The fact that the S-350, S-500, S-550 were highlighted together indicates that of the above mentioned possibilities, the S-550 is most likely to be a replacement for the S-400 which was the most major system not mentioned. Other possibilities are numerous, including a more specialised version of the S-500 intended for a specific role such as anti-satellite warfare.