MOSCOW, March 21 (Reuters) - Following are biographical details of some of the 20 Russians targeted on an expanded U.S. sanctions list announced by President Barack Obama on Thursday.
SERGEI IVANOV, 61, is a former senior foreign intelligence officer who held the posts of Defence Minister and Deputy Prime Minister under Putin. He is now head of the presidential administration. Ivanov - an old friend of President Vladimir Putin - has known his boss since his KGB service in the 1970s and is one of the most influential conservatives from the security world, a group known as the "Siloviki". Ivanov was a rival to Dmitry Medvedev to succeed Putin as president when Putin stepped aside for four years to become prime minister in 2008 because of constitutional limits.
ALEXEI GROMOV, 53, is deputy head of the Kremlin administration and a close ally of Putin who was also a senior official under Boris Yeltsin, Russian president in the 1990s. During his tenure, the Kremlin cracked down on the media, ensuring the most influential outlets are now in the hands of the state or loyal businessmen and companies.
IGOR SERGUN, 57, heads Russia's military intelligence service GRU. This operates under the Russian Joint Staff which designs and carries out all military operations. Russia has however denied that any of its forces are operating in the Ukrainian region of Crimea.
VLADIMIR KOZHIN, 55, worked with Putin in the president's home city of St Petersburg in the 1990s and followed him to the Kremlin, occupying the post of chief property manager.
ARKADY ROTENBERG, 62, is a former judo sparring partner of Putin. He controls energy service company Stroygazmontazh and is a shareholder in construction group Mostotrest, which won lucrative contracts in Sochi before the 2014 Winter Olympics.
BORIS ROTENBERG, 57, is Arkady's younger brother and business partner and, like Putin, hails from St Petersburg and is a judo fan as well as a former sparring partner. He is a member of the board of SMP Bank and vice-president of the Russian Judo Federation.
GENNADY TIMCHENKO, 61, is a long-standing ally of Putin and was co-owner of trading house Gunvor until he sold his shares this week. His company's spectacular rise has long attracted controversy because he has such strong ties to Putin. In announcing the sanctions, the U.S. Treasury Department said Putin himself has investments in the world's No. 4 oil trading company. This provoked a quick and furious response from Gunvor, which said the statement was "outrageous" and "blatantly false".
YURI KOVALCHUK, 62, an old acquaintance of Putin, part-owns and chairs St Petersburg-based Bank Rossiya. He and Putin were both in a group of friends and associates that set up a housing community known as Ozero (Lake), grouping together their dachas, or country houses, outside St Petersburg.
VLADIMIR YAKUNIN, 65, also knew Putin from his St Petersburg days and was part of the Ozero housing cooperative. After serving as a Soviet diplomat at the United Nations, Yakunin arrived back in Russia around the same time that Putin returned from his KGB posting in Dresden and worked in local government. After Putin became president in 2000, Yakunin had a spell in government, and went to join Russian Railways, a vast state company, in 2003. He became the head of Russian Railways in 2005 and still holds the post which controls what amounts to the blood supply of the world's largest country.
ANDREI FURSENKO, 64, is a Kremlin aide and long-time friend of Putin from St Petersburg. A member of the Ozero housing cooperative, he was education minister form 2004 until 2012 and was a founder member of Bank Rossiya. (compiled by Megan Davies; editing by David Stamp and Timothy Heritage)