The S-75 Dvina (Russian: С-75; NATO reporting name SA-2 Guideline) is a Soviet-designed, high-altitude air defense system, built around a surface-to-air missile with command guidance. Since its first deployment in 1957 it has become the most widely deployed air defense system in history. It scored the first destruction of an enemy aircraft by a surface-to-air missile, shooting down a Taiwanese Martin RB-57D Canberra over China, on October 7, 1959, hitting it with three V-750 (1D) missiles at an altitude of 20 km (65,600 ft). The success was attributed to Chinese fighters at the time in order to keep the S-75 program secret.
This system first gained international fame when an S-75 battery, using the newer, longer-range and higher-altitude V-750VN (13D) missile shot down the U-2 of Francis Gary Powers overflying the Soviet Union on May 1, 1960. The system was also deployed in Cuba during the Cuban Missile Crisis, where on October 27, 1962, it shot down a U-2 overflying Cuba flown by Rudolf Anderson, almost precipitating nuclear war. North Vietnamese forces used the S-75 extensively during the Vietnam War to defend Hanoi and Haiphong. It has also been locally produced in the People's Republic of China using the names HQ-1 and HQ-2.