There was no indication that the Western governments knew of any significant holdings that could be tied to Putin.

It's not known what Mr. Putin owns or where it could be. Billions of dollars have flowed through the accounts of his close friends and family members, despite the fact that the extent of his wealth remains opaque.

According to his public financial disclosures, Mr. Putin earns $140,000 a year and has a small apartment.

The Russian president's Palace, a vast estate on the Black Sea estimated to have cost more than $1 billion, is not included in that. The disclosures wouldn't account for Putin's Yacht, a $100 million luxury vessel long tied to him in speculative news reports. The yacht, Graceful, was tracked leaving Germany for Russia just weeks before the invasion of Ukraine.

There is a $4.1 million apartment in Monaco that was purchased by a woman who is said to be Mr. Putin's lover. The villa in the South of France is linked to his ex-wife.

None of these assets can be connected to the Russian president, which is a problem for the United States and its allies.

Western governments have focused their sanctions on people who are suspected of being Mr. Putin's proxies. Most of the new penalties are aimed at people close to Mr. Putin. Kirill Shamalov, his former son-in-law and a major shareholder in a Russian petrochemical firm, is one of them.

A $100 million yacht, known as Graceful, that is said to be connected to Mr. Putin.Credit...Marcus Brandt/picture alliance, via Getty Images

The sanctions announced this past week would make it impossible for those targeted to access assets or conduct financial transactions in the United States, Britain and the European Union. Money and property that could be traced back to those on the list would be out of reach.

Russia's elites, who have lived under Western sanctions for most of the last decade, have long favored complex mazes of corporate ownership to avoid scrutiny. Their wheeling and dealing only surfaces publicly with the leak of files from offshore law firms or secretive banks that cater to those wanting to hide their wealth.

It was not always clear to American officials what assets would be affected by Russia sanctions, according to Paul Massaro, a senior adviser at the U.S. Helsinki Commission.

It means that the sanctions that we hit these people with are mostly going to be press releases, because we don't know what assets they have.

Even if the United States only has a limited picture of Mr. Putin, sanctions are still worth it.

The symbolic value of the effort was emphasized by a European diplomat.

By being added to the U.S. Treasury Department's Designated Nationals list, Mr. Putin joins a small but notorious subgroup of heads of state. Russia's foreign minister was also subject to the sanctions.

We are united with our international allies and partners to ensure that Russia pays a severe economic and diplomatic price for its invasion of Ukraine.

Estimates of what Mr. Putin may be worth vary widely. One of the most sensational claims came from Bill Browder, an American-born financier who was banned from Russia in 2005. He testified before Congress that he believed Mr. Putin could be the richest man in the world at the time.

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What is the root of this invasion? Russia considers Ukraine to be within its sphere of influence, and it is worried that the country might join NATO or the European Union. The United States and Europe give financial and military aid to Ukraine.

Are these tensions starting now? The Russian military crossed into Ukrainian territory after the overthrow of their Russia-friendly president. There was a cease-fire in 2015, but fighting continues.

How has the Ukrainians responded? The state of emergency was declared after cyberattacks knocked out government institutions. Volodymyr Zelensky declared martial law after the attacks. The foreign minister called for the world to stop the attacks.

The author of the book "Russia's Crony Capitalism" pegged the Russian president's wealth at $125 billion. He claimed that it could be hidden in a web of offshore havens held by Mr. Putin's friends and relatives.

On rare occasions, people in Mr. Putin's inner circle talk about his wealth. In 2010, Sergei Kolesnikov wrote an open letter to Russia's president, saying that Mr. Putin was building an enormous estate on the Black Sea coast. It had cost more than $1 billion through corruption, bribery and theft, according to a letter written by Mr. Kolesnikov after he left Russia.

“Putin’s Palace” has a complex ownership history that does not include the Russian president.Credit...Navalny Life, via Associated Press

According to a report and documentary released last year by the jailed opposition leader, the huge project features a movie theater, a hookah lounge and a pole-dancing stage. Mr. Shamalov's father has been involved with several of Mr. Putin's associates. A childhood friend of the Russian president, Arkady Rotenberg, claimed last year that he owned the property and was going to develop it into a hotel and apartments.

The Kremlin insists that Mr. Putin is a simple man and that he doesn't own any palaces.

The state television host said on his show early last year that Putin has no need for luxury.

Even if Mr. Putin does not appear in the data himself, there are still clues about his proximity to wealth. The Panama Papers, a trove of files from an offshore law firm that were exposed in 2016, revealed the secret wealth of many close to him, including Sergei Roldugin, a cellist and longstanding friend who took in more than $8 million a year. He had previously told The New York Times that he didn't have millions.

Last year, a new leak of files from companies specializing in offshore tax shelters, called the Pandora Papers, showed that the woman said to be Mr. Putin's lover had acquired an apartment in Monaco. She had accumulated a number of assets that were worth an estimated $100 million.

Mr. Putin doesn't need a lot of money because he is an autocrat, according to a researcher at the Hudson Institute.

He asked if they were really saying that he was going to cash in and retire to St.

The reporting was contributed by Anton Troianovski.