Semion Yudkovich Mogilevich is a Jewish Ukrainian-born Russian organized crime boss. He quickly built a highly structured criminal organization, in the mode of an American mafia family; many of the organization's 250 members are his relatives. He is described by agencies in the European Union and United States as the "boss of all bosses" of most Russian Mafia syndicates in the world, he is believed to direct a multibillion-dollar international criminal empire and is described by the Federal Bureau of Investigation (FBI) as "the most powerful and dangerous gangster in the world," with immense power and reach at a global scale, and connections to prominent government, military, and law enforcement officials, and powerful politicians around the world. He has been accused by the FBI of "weapons trafficking, contract murders, extortion, drug trafficking, and prostitution on an international scale."

The Russia–Ukraine gas disputes refer to a number of disputes between Ukrainian oil and gas company Naftogaz Ukrayiny and Russian gas supplier Gazprom over natural gas supplies, prices, and debts. These disputes have grown beyond simple business disputes into transnational political issues—involving political leaders from several countries—that threaten natural gas supplies in numerous European countries dependent on natural gas imports from Russian suppliers, which are transported through Ukraine. Russia provides approximately a quarter of the natural gas consumed in the European Union; approximately 80% of those exports travel through pipelines across Ukrainian soil prior to arriving in the EU.