Buran (Russian: Бура́н, IPA: [bʊˈran], Snowstorm or Blizzard) was a Soviet and later Russian reusable spacecraft project that began in 1974 at TsAGI and was formally suspended in 1993. It was a response to the United States Space Shuttle program. The project was the largest and the most expensive in the history of Soviet space exploration. Development work included sending the BOR-5 on multiple sub-orbital test flights, and atmospheric flights of the OK-GLI.