S-75AK (NATO codename SA-2E): Fan Song-E radar and V-750AK missiles. Similar rocket to the V-750SM, but with a bulbous warhead section lacking the older missile's forward fins. The S-75AK is long, has a body diameter of , and weighs at launch. The missile can be fitted with either a command-detonated 15 kt nuclear warhead or a conventional HE warhead. S-75SM (NATO codename SA-2F): Fan Song-F radar and V-750SM missiles. After watching jamming in Vietnam and the Six-Day War render the S-75 completely ineffective, the existing systems were quickly upgraded with a new radar system designed to help ignore wide-band scintillation jamming. The command system also included a home-on-jam mode to attack aircraft carrying strobe jammers, as well as a completely optical system (of limited use) when these failed. Fs were developed starting in 1968 and deployed in the USSR later that year, while shipments to Vietnam started in late 1970. SA-2 FC: Latest Chinese version. It can track six targets simultaneously and is able to control 3 missiles simultaneously. S-75M Volga (Russian - Volga River). Version from 1995. Volkhov M-2 (NATO codename SA-N-2) naval variant M-3 (NATO codename SA-NX-2) (missile V-800, V-760/755) experimental variant with four short wrap-around boosters forward, like the Seaslug system from the UK. As previously mentioned, most nations with S-75s have matched parts from different versions or third-party missile systems, or they have added locally produced components. This has created a wide variety of S-75 systems which meet local needs. HQ-1 (Hong Qi, Red Flag): Chinese variant with additional ECCM electronics to counter the System-12 ECM aboard U-2s flown by the Republic of China Air Force Black Cat Squadron. HQ-2: Upgraded HQ-1 with additional ECCM capability to counter the System-13 ECM aboard U-2s flown by Republic of China Air Force Black Cat Squadron. Upgraded HQ-2s remain in service today, and the latest version utilizes Passive electronically scanned array radar designated SJ-202, which is able to simultaneously track and engage multiple targets at and , respectively. The adoption of multifunction SJ-202 radar has eliminated the need to have multiple, single-function radars, and thus greatly improved the overall effectiveness of the HQ-2 air defence system. A target drone version is designated BA-6. HQ-3: Development of HQ-2 with maximum ceiling increased to 30 km, specifically targeted for high altitude and high speed spy planes like SR-71. Maximum range is 42 km and launching weight is around 1 ton, and