after overcoming the technical difficulties of producing the 2K12 "Kub" the system was accepted into service on 23 January 1967 and went into production that same year. It is sometimes claimed that the M-11 Shtorm naval system is a version of the 3M9 but this is not the case, as the M-11 Shtorm is a separate system and, unusually for Russian surface-to-air missiles, has no land-based variant. The 2K12 "Kub" was recommended for modernisation work in 1967 with the goal of improving combat characteristics (longer range, improved ECCM, reliability and reaction time) established for the new chief designer Ardalion Rastov. A modernised variant underwent trial testing in 1972 eventually being adopted in 1973 as the "Kub-M1". The system underwent another modernisation between 1974 and 1976, again the general combat characteristics of the system were improved with the "Kub-M3" clearing testing and entering service in 1976. After the Rastov visit to Egypt in 1971 to see Kub in operation he decided upon the development of a new system, called Buk, where each TEL should have its own fire control radar (TELAR) and is able to engage multiple targets from multiple directions at the same time. The final major development of the Kub missile system was achieved during the development of its successor, the 9K37 "Buk" in 1974. Although the Buk is the successor to Kub it was decided that both systems could share some interoperability, the result of this decision was the "Kub-M4" system. The Kub-M4 used Kub-M3 components which could receive fire control information from the 9А310 transporter erector launcher and radar (TELAR) of the 9K37 Buk. The advantage of interoperability was an increase in the number of fire control channels and available missiles for each system as well as a faster service entry for Buk system components. The Kub-M4 was adopted into service in 1978 following completion of trials. Some early development implementations of the Buk missile system heavily utilized Kub components, including the 3M9 missile. There are several plans to integrate active radar homing missiles into Kub. For instance, Polish WZU of Grudziadz demonstrated a project of a Sparrow-armed Kub at the MSPO 2008 defence exhibition in Kielce. It is reported also that Vympel initiated some work to use its RVV-AE air-to-air missile to modernise the Kvadrat SAM system. Also, the Czech company RETIA presented a SURN (fire control radar) upgrade featuring an optical channel and new multiple-function