The U.S. has announced additional sanctions against Russia, following alleged atrocities committed by Russian troops in Ukraine. Among those on the latest list of sanctions are two adult daughters of President Vladimir Putin.

"We believe that many of Putin's assets are hidden with family members and that's why we're targeting them," a senior Biden administration official said in a call with reporters on Wednesday.

Putin has refused to publicly acknowledge the names of his children, but the Treasury Department identified the daughters being sanctioned as Maria Vladimirovna Vorontsova and Katerina Vladimirovna Tikhonova. One is a pediatric endocrinologist, the other a former competitive dancer turned tech executive.

Putin is intensely private when it comes to his family, and many details about his children have been scarce and shrouded in secrecy. Here's what we know about them.

Putin rarely speaks publicly about his children

Both are the daughters of Putin's ex-wife, Lyudmila Putina, an Aeroflot flight attendant who Putin married in 1983. The two later divorced after three decades of marriage.

One of the few times Putin has spoken about his children came during a news conference in 2015, according to the BBC. "My daughters live in Russia and studied only in Russia, I am proud of them," Putin said. "They speak three foreign languages fluently. I never discuss my family with anyone."

"Every person has a right for their fate, they live their own life and do it with dignity," he said.

In Russian public life, the daughters are not identified as Putin's children and for years they were kept out of the spotlight. But their profiles have slowly risen in the last several years as they have taken on influential positions inside the country.

Putin's eldest daughter is an endocrinologist

Maria Vladimirovna Vorontsova is known by several other last names: Faassen is her married surname, and she sometimes is also called Maria Putina. Her nickname is Masha.

Born in 1985, Vorontsova now works as a pediatric endocrinologist and genetics researcher. She is listed as a doctor at the Endocrinology Research Center Moscow, though she's the only physician on the center's website without a photo. The site identifies Vorontsova as Deputy Chairman of the Russian Society of Young Endocrinologists, and says she speaks English, German, French and Dutch.

"Vorontsova leads state-funded programs that have received billions of dollars from the Kremlin toward genetics research and are personally overseen by Putin," according to the Treasury Department.

She appeared in a 2019 interview on Russian television, speaking about children's obesity and diabetes.

In addition to her medical research, she reportedly has business interests. BBC Russia reports that Vorontsova is co-owner of a company that's "involved in the implementation of the largest private investment project in Russian healthcare."

Vorontsova is married to a Dutch businessman named Jorrit Joost Faassen, who the BBC reports once worked for the Russian energy giant Gazprom. The two are thought to have separated.

His second daughter is a competitive dancer turned tech executive

Katerina Vladimirovna Tikhonova was born in Germany in 1986 while Putin was stationed there for the KGB. Her nickname is Katya.

Tikhonova's last name is a derivation of her grandmother's name, according to Reuters. For years, she was a competitive acrobatic dancer, and several videos of her energetic performances with partner Ivan Klimov are online.

Today, she is "a tech executive whose work supports the [Government of Russia] and defense industry," the U.S. Treasury says.

In 2015, Bloomberg reported on a new $1.6 billion startup incubator and science center next to Moscow State University – to be run by Tikhonova. At the time, she headed the National Intellectual Reserve Center and was a member of the economic board at Moscow State.

Tikhonova spoke at the St. Petersburg International Economic Forum – Russia's version of Davos – last year about international investment disputes. At the conference, she was identified as the deputy director for the Institute for Mathematical Research of Complex Systems at Moscow State University.

Tikhonova was reportedly married to Kirill Shamalov, a shareholder of a Russian petrochemicals company and the son of a longtime acquaintance of Putin from St. Petersburg.

A 2015 Reuters investigation put the couple's corporate holdings at about $2 billion, primarily from Shamalov's petrochemicals stake. The couple also owned a villa in Biarritz, France, with an estimated value of $3.7 million, according to Reuters.

The two reportedly split in 2018.

Putin is a grandfather. And he may have other children

In a 2017 televised Q&A reported by Russian news agency TASS, Putin said he had recently welcomed a second grandchild, and explained why he shields his family from scrutiny.

"You see, I do not want them to be brought up as 'blue bloods.' I want them to grow up as normal people," he said.

"As soon as I state their ages, names, they would be identified immediately, and any enormous interest would damage the kids' development," Putin said. "So, everything is fine, and I am asking you to understand me correctly and to respect this position."

His current partner is thought to be former Olympic gold medal rhythmic gymnast Alina Kabaeva, though Putin has refused to confirm their relationship.

When a reporter asked Putin about his relationship with Kabaeva, Newsweek reports that Putin responded: "I am, of course, aware of the cliché that politicians live in glass houses, but even in these cases, there must be some limits ... I always disliked people who go around with their erotic fantasies, sticking their snot-ridden noses into another person's life."

The two are thought to have several children together, and Kabaeva is rumored to be currently ensconced in Switzerland.

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