The three biggest names on the list of Russian nationals sanctioned by the US on Friday are Oleg Deripaska, Viktor Vekselberg, and Alexander Torshin.

Torshin and Deripaska are known to have been in indirect contact — through their associates — with members of Donald Trump's 2016 presidential campaign.

Vekselberg, meanwhile, is one of six Russians aligned with Russian President Vladimir Putin who attended Trump's inaugural celebrations in January 2017.

Two of Vekselberg's US associates donated a combined $1.25 million to Trump's inaugural committee.

The laundry list of names included in the US's latest round of sanctions against Russia leaves no doubt that it's targeting Russian President Vladimir Putin's closest associates as the Kremlin ramps up its aggression around the globe.

But three names stand out from the list: Oleg Deripaska, Viktor Vekselberg, and Alexander Torshin:

Deripaska and Vekselberg are two of seven sanctioned oligarchs closely tied to Putin. The others are Kirill Shamalov, Suleiman Kerimov, Andrei Skoch, Igor Rotenberg, and Vladimir Bogdanov.

Torshin was included on a list of 17 senior Russian government officials who were penalized and had their assets frozen.

Torshin and Deripaska are known to have been in indirect contact with members of President Donald Trump's campaign through their associates before the 2016 election.

Vekselberg was one of at least six Putin-allied Russians who attended Trump's inaugural festivities in January 2017.

Two of Vekselberg's US associates donated a combined $1.25 million to Trump's inaugural committee, and he also has business ties to Commerce Secretary Wilbur Ross.

Deripaska's ties to Paul Manafort draw scrutiny

Paul Manafort. Chip Somodevilla/Getty Images

Deripaska has drawn significant attention over the past year for his ties to Paul Manafort, the former chairman of Trump's campaign.

The Russian-Ukrainian billionaire and aluminum magnate is a longtime ally of the Kremlin. Manafort's relationship with Deripaska, meanwhile, stretches back years and relates to the two men's work pushing pro-Russia interests on the world stage.

Things haven't always been rosy between them. In legal complaints filed in the Cayman Islands in 2014, Deripaska's representatives said Manafort disappeared after Deripaska gave him and his longtime associate Rick Gates $19 million to invest in a Ukrainian TV venture in 2007 that ultimately failed.

Last year, The Washington Post reported on emails between Manafort and Konstantin Kilimnik, a former Russian intelligence officer, that raised questions about whether Manafort may have pushed a pro-Russia campaign platform to pay off his debt to Deripaska.

According to The Post, beginning in April 2016, Manafort offered to give Deripaska "private briefings" about the Trump campaign and asked Kilimnik how he could use his elevated role in the campaign to "get whole" with Deripaska.

At the end of July, Kilimnik wrote in an email to Manafort that he had "met today with the guy who gave you your biggest black caviar jar several years ago," a reference to Deripaska's previous loans to Manafort.

"We spent about 5 hours talking about his story, and I have several important messages from him to you," he wrote.

Three days later, Manafort and Kilimnik met in New Jersey. Manafort has said he and Kilimnik discussed the Trump campaign and the hack of the Democratic National Committee, while Kilimnik says they did not discuss the campaign but talked about "current news" and "unpaid bills."

Last week, Vice News reported that a private jet linked to Deripaska arrived in New Jersey shortly after the meeting between Manafort and Kilimnik.

The energy tycoon whose associates donated over $1 million to Trump's inauguration

US President Donald Trump at his inauguration. Thomson Reuters

Vekselberg, the Russian energy mogul who was among the seven oligarchs targeted in the latest sanctions, has not attracted the same level of media scrutiny as Deripaska, but he is no less influential.

Vekselberg is the founder of the Renova Group, a Russian conglomerate with a range of interests in Russia's energy sector. He frequently meets with Putin to discuss business.

This week, there was significant speculation that Vekselberg may have been among at least three Russian oligarchs questioned in connection with the special counsel Robert Mueller's investigation into Russia's interference in the 2016 US election.

Mueller's focus on Russian oligarchs comes as investigators are looking into whether wealthy Russians illegally funneled money, either directly or indirectly, into Trump's campaign or inauguration. Prosecutors are also said to be interested in whether wealthy Russians used American donors or US companies with political action committees to infuse money into the election.

Vekselberg was one of at least six Putin-allied Russians who attended Trump's inaugural celebrations in January 2017. Citing federal filings, The Post reported that two of Vekselberg's US associates donated a combined $1.25 million to Trump's inaugural committee.

Last year, Mother Jones reported that Renova Group partnered with Commerce Secretary Wilbur Ross to take over the Bank of Cyprus. Democratic lawmakers sent Ross a list of questions during his confirmation hearings in February 2017 about his relationship with Vekselberg. He has not answered them.

'President Putin's emissary' in the US

Alexander Torshin. AP

Torshin, the Russian banker and politician who was one of the 17 senior Russian government officials hit with sanctions on Friday, is under investigation by the FBI, which is looking into whether he illegally funneled money into the National Rifle Association.

The NRA said it spent a record $55 million on the 2016 elections, most of which came from a sector of the organization that isn't required to disclose its donors. About $30 million of that was spent on backing Trump or opposing the Democratic nominee, Hillary Clinton.

The NRA has emphasized and news reports have confirmed that Torshin, not the organization, is under investigation by the FBI.

Torshin attended the NRA's convention every year from 2012 to 2016 — occasionally with Maria Butina, his longtime assistant and representative — and has met every NRA president since 2012, according to NPR.

Torshin's NRA credentials earned him a post as an election monitor in the November 2012 race between Barack Obama and Mitt Romney.

Butina, meanwhile, has been cultivating her own ties with American gun-rights advocates, like the Republican strategist Paul Erickson, with whom she has been acquainted since at least 2013.

Erickson invited scrutiny last year when reports emerged that he tried to arrange a back-door meeting between Trump and Putin, with Torshin acting as "President Putin's emissary on this front." Butina made a similar request to the Trump campaign through another right-wing advocate.

Neither Trump nor his campaign is known to have entertained the request. Torshin and Donald Trump Jr., the president's eldest son, attended a separate NRA dinner the same night.