MOSCOW (Reuters) -The United States has imposed sanctions on Russia's largest oil companies, Lukoil and Rosneft, in Washington's toughest measures on Russian business since the start of the war in Ukraine. Here are some details about the two companies, which together account for around half of Russia's oil output: ROSNEFT * The company is led by Igor Sechin, a longtime ally of Russian President Vladimir Putin. * It produced some 3.7 million barrels per day (bpd) of oil and gas condensate in 2024, accou ...