U.S. President Barack Obama imposed financial sanctions on several billionaire associates and top aides of President Vladimir Putin as he increased pressure on Russia. Kremlin spokesman Dmitry Peskov said Russia’s reaction will be “reciprocal and swift” after Russia barred nine U.S. lawmakers and officials in retaliation against earlier measures.

The following is a list of those targeted. They are all now subject to travel bans and asset freezes.

*Gennady Timchenko:

Timchenko, 61, has a fortune of $8.5 billion according to Bloomberg Billionaire’s Index, became acquainted with Putin in the 1990s. He sold his entire 44 percent stake in Gunvor Group Ltd. to his business partner Torbjorn Tornqvist on March 19, to avoid disrupting operations. One of the largest commodity traders in the world, Gunvor had revenue of $93 billion in 2012. The U.S. Treasury said Putin is an investor in the trader and may have access to its funds, while Timchenko’s activities in the energy sector “have been directly linked to Putin.”

Gunvor said on its Twitter Inc. account that Putin has never had any ownership in it, beneficial or otherwise, as did Timchenko’s investment company, Volga Group. Peskov declined to comment on the allegations. Timchenko is a Finnish citizen and has a mansion on Lake Geneva. He restored his Russian citizenship in 2012 and began investing in the country after a U.S. investigation was opened into Gunvor over manipulating oil markets, fraud and money laundering. He owns 23.5 percent of OAO Novatek, Russia’s second largest gas producer, and 31.5 percent of OAO Sibur Holding, Russia’s largest chemicals maker.

*Arkady Rotenberg, Boris Rotenberg:

The brothers are business partners, each worth about $3 billion, according to data compiled by Bloomberg. Arkady, 62, a boyhood friend and former judo partner of Putin, gained his fortune by selling pipes and building pipelines for state-run OAO Gazprom, the world’s largest natural gas producer. His companies were awarded more than 227 billion rubles ($6.3 billion) in contracts for the 2014 Sochi Winter Olympics, according to figures compiled from corporate and government filings.

Arkady Rotenberg told the Financial Times in an interview published in November 2011 that while he values Putin’s friendship, he’d never abuse it for personal gain. Boris is 57. Andrei Baturin, spokesman for the Rotenbergs’ Stroygazmontazh, declined to comment immediately.

*Yury Kovalchuk:

Kovalchuk, 62, is worth $1.16 billion according to CEO magazine. He’s the largest shareholder in Bank Rossiya, sanctioned today by the U.S. Treasury, which described Kovalchuk as a personal banker for Putin and other senior Russian officials. Bank Rossiya controls Sogaz, one of the largest Russian insurance companies, which is headed by the son of Putin’s chief of staff, Sergei Ivanov. Kovalchuk controls National Media Group, which owns television assets including one of Russia’s two biggest channels, Channel One, and the Izvestia newspaper.