It was founded in 1992 and its chairman first Alexei Miller. Former Russian president and prime minister Dmitri Medvedev previously served as chairman of Gazprom.
Russia ranks as Ukraine's principal supplier of oil and Russian firms now own and/or operate the majority of Ukraine's refining capacity. Natural gas imports come from Russia and Turkmenistan, which deliver the gas through a pipeline system owned and controlled by Gazprom, Russia's state-owned gas monopoly. In 2005 and 2006, Ukraine switched from barter to cash payments for gas imports. Ukraine controls the gas pipelines on its territory that are also used to transit Russian gas to Western Europe. The complex relationship between supplier, transporter, and consumer has led to some tensions, including Russia's decision to cut off gas supplies for three days in January 2006.