Russian oil company Gazprom Neft, a subsidiary of the energy giant Gazprom, has been given 45 days to divest from its ownership of the Serbian oil company NIS following new US sanctions targeting the Russian oil sector.

Oil had a dramatic day as the US imposed its most aggressive sanctions on Russia’s industry and prices surpassed $80 a barrel. Brent futures at one point hit their highest mark since early October. The sweeping penalties are part of an effort by the outgoing Biden administration to boost Ukraine’s leverage in possible peace negotiations after Donald Trump takes office.