WASHINGTON -- The United States has added nearly three dozen people and companies to its sanctions list for activity directly or indirectly connected to the conflict in eastern Ukraine and the annexation of the Crimean Peninsula.
The Kremlin reacted swiftly to the December 22 announcement, calling it unfriendly and threatening unspecified countermeasures.
The U.S. move also comes a day after the European Union opted to extend its own sanctions against Russia.
The list, released by the U.S. Treasury Department, included several companies connected to Russian businessmen with close ties to President Vladimir Putin's Kremlin. They include oil trader Gennady Timchenko and Arkady and Boris Rotenberg, brothers who have been judo partners of Putin and who control sprawling industrial conglomerates believed to be worth billions.
All were previously sanctioned under earlier rounds announced in 2014, imposed after Russia annexed the Ukrainian Black Sea peninsula of Crimea in March.
The sanctions would only be eased, an accompanying statement said, when Russia abides by the Minsk peace agreement "including the return to Ukraine of control of its side of the international border with Russia."
Several top officials in the self-declared "people's republics" of Donetsk and Luhansk, regions of eastern Ukraine now mostly under separatist control, were targeted in the new list, including Sergei Tsyplakov and Vasily Nikitin, who have claimed the titles of prime minister and deputy prime minister of the "Luhansk People's Republic."
The Treasury Department also expanded the list of former officials connected to the government of Viktor Yanukovych, who was ousted as Ukraine's president after months of protests in the capital, Kyiv, that culminated in violence in February 2014.
Among the two added to the updated list was Vitaliy Zakharchenko, the former interior minister who the Treasury Department said gave the order for police to fire on protesters during the 2014 protests.
Several subsidiaries of state-run companies including banks VTB and Sberbank and Rostec, a conglomerate encompassing many leading Russian defense firms.
In Crimea, which has been cut off economically from Ukraine and which Russia is struggling to integrate into its economy, three wineries were targeted for inclusion, along with a film studio, a health resort, and several banks.
Kremlin spokesman Dmitry Peskov told Russian news agencies that Moscow was considering countermeasures in response to the expanded U.S. list.
"This is continuation of the unfriendly line against Russia, which runs counter to logic," TASS quoted him as saying. "This is continuation of the line that is having devastating effects on bilateral relations."
More than 9,000 people have been killed in fighting between government forces and Russian-backed separatists since April 2014.