Vladimir Putin's inner circle: Who's who, and how are they connected?

As the head of one of the world's largest oil companies, Rosneft, Igor Sechin is one of the most powerful men in Russia.

Like Putin, Sechin has come a long way since the early 1990s when the two men worked together in the St Petersburg mayor's office. After he followed Putin to Moscow, Sechin continued to work closely with his old boss -- both as his presidential aide and then as deputy prime minister.

In 2014, after Russia annexed Crimea from Ukraine, and after his stint in Putin's administration, Sechin was put under sanctions by the US treasury which said he had "shown utter loyalty to Vladimir Putin - a key component to his current standing."

With a fortune of about $15.5bn, Gennady Timchenko is ranked 85 on Forbes' billionaires list.

Although he has a luxurious lifestyle now -- and played hockey with Putin -- he has not always been so wealthy. Timchenko comes from humble beginnings -- his wife Elena said the couple used to live in a communal apartment in St Petersburg with "bedbugs and the smell of borscht soup in the kitchen." Their elder daughter, she said, first slept in a suitcase in their room.

Timchenko says he has known Putin for more than 20 years but says "when I am asked questions about our friendship, I always say, please turn to Vladimir Vladimirovich. If I call myself a friend of his, it wouldn't look appropriate."

Timchenko is one of the founders of Gunvor -- a global company that trades in oil and energy markets.

Like other members of Putin's inner circle, Timchenko has been sanctioned, forcing him to ground his private jet in Moscow after Gulfstream refused to service the aircraft.

The US Treasury has claimed that "Timchenko's activities in the energy sector have been directly linked to Putin. Putin has investments in Gunvor and may have access to Gunvor funds." Gunvor has denied this, saying "President Putin has not and never has had any ownership, beneficial or otherwise in Gunvor."

After being slapped with sanctions, Timchenko is reported to have said "you have to answer for everything, even your friendship with the president."

As a sign of Timchenko's closeness to Putin, he was gifted a puppy by Putin from his beloved dog Connie, according to Russian media reports.

Russia's prime minister, Dmitry Medvedev, and Putin go a long way back. Both of them are from St Petersburg and worked for mayor Anatoly Sobchak in the early 1990s.

After Putin moved to Moscow and became Prime Minister, Medvedev followed him and was appointed deputy chief of staff to the President.

In 2008 he and Putin implemented a controversial power sharing agreement. At that time, Putin had already served two terms as president and was constitutionally barred from serving a third consecutive term. Medvedev became president and Putin became prime minister. Four years later, they swapped back again.

The two men are close; in 2015 they were shown in a video working out in Putin's gym in Sochi and barbecuing their breakfast together.

Vladimir Putin's daughter Katerina -- who is said to be an academic and an acrobatic rock 'n' roll dancer -- is reportedly married to Kirill Shamalov. He is the son of Nikolai Shamalov, an old friend of Putin's from St Petersburg.

Nikolai Shamalov helped co-found the Ozero cooperative -- an elite dacha community built near St Petersburg in the 1990s, of which Putin is also member.

Nikolai's son Kirill is said to be one of Russia's youngest billionaires with a stake in Sibur, a Russian petrochemical processor.

Nikolai Shamalov has been sanctioned by the European Union for being a "long-time acquaintance" of Putin and for benefiting from "his links with Russian decision-makers."

Sergei Roldugin is a concert cellist from Putin's home city of St Petersburg. He introduced Putin to his former wife Lyudmila and is also godfather to Putin's elder daughter Maria.

Roldugin was thrust into the media spotlight in 2016 when leaked documents, dubbed the Panama Papers, alleged he fronted a number of offshore shell companies which saw hundreds of millions of dollars of Russian loans and lucrative contracts pass through their books.

Roldugin has not responded to CNN regarding the leak but has previously said he does not "have millions."

Shortly after the Panama papers were published, Roldugin travelled to Syria to take part in a concert overseen by the Russian Ministry of Defense and the Mariinsky Theatre in the ancient ruins of Palmyra.

Vladislav Surkov has been dubbed Putin's "gray cardinal" by the media. He is said to be a powerful decision maker behind the scenes in Russia and is Putin's presidential aide -- a role previously filled by Igor Sechin.

He coined the term "sovereign democracy" which proposes a strong state to guard against chaos and stop foreign meddling.

In 2014 Surkov was accused by the European Union of directly helping Russia to annex Crimea from Ukraine.

He has also been sanctioned by the United States. After the sanctions were imposed, Surkov told one Russian newspaper that this was a "great honor."

In 2016 a Ukrainian hacking group claimed to have broken into an email account which belonged to Surkov. The group released a series of emails which they said detailed Russian attempts to destabilize Ukraine. Commenting on the allegations at the time, Dmitry Peskov, spokesman for Vladimir Putin, said Surkov "does not use email."

Vyacheslav Volodin is the speaker of the State Duma, Russia's parliament. Before he took up the role in 2016, he had spent five years running the Kremlin's domestic policy.

Volodin, who replaced Vladislav Surkov as first deputy chief of staff to the Russian President, took over after huge post-election protests in Russia in 2011, which threatened Putin's power.

Following the 2011 protests, Volodin worked on consolidating the power of the ruling party and on softening Putin's image, according to the Carnegie Moscow Center.

Volodin has been sanctioned by the United States which says Putin's decision to annex Crimea from Ukraine "is believed to have been based on consultations with his closest advisers, including Volodin."

According to an interview Sergey Chemezov gave to a Russian newspaper, he and Putin have known each other for more than 30 years.

The pair both served as KGB agents in East Germany, when their families lived in the same building, and they became "friendly neighbors."

Chemezov has worked in the Russian President's administration and has held a series of top posts at state-owned companies.

He is under US sanctions and is considered by the US to be a "trusted ally of President Putin."

Yury Kovalchuk is Putin's personal banker, according to the US Treasury, which says he is known as one of the Russian President's "cashiers."

Kovalchuk, the largest shareholder in Bank Rossiya, was sanctioned by the US in 2014.

Like Putin and the Shamalovs, Kovalchuk is also a founding member of the elite Ozero dacha cooperative near St Petersburg.

In 2013, it was reported that he had hosted the wedding of Putin's daughter, Katerina, to Kirill Shamalov at his ski resort near Ozero.

Following the introduction of sanctions, Kovalchuk said he had been concerned Bank Rossiya would collapse as people tried to withdraw their money. Instead, he told Russia 24 state TV, Putin opened an account and "the bank was flooded with people."

According to the Russian newspaper Kommersant, Arkady and Boris Rotenberg are Putin's childhood friends, having known him for more than 40 years. In an interview with the paper, Arkady Rotenberg said he first met Putin aged 12 when they went to the same judo class.

The trio has been pictured playing ice hockey together.

Both brothers are on the US sanctions list.

The US Treasury says the Rotenbergs have benefited from their closeness to Putin after he awarded them around $7 billion in contracts for the Sochi Winter Olympics.

Arkady Rotenberg has said that being on the sanctions list makes him more "concentrated," and that it is a "positive" thing.