PALMA DE MALLORCA, Spain — The American government seized a mega yacht in Spain owned by an oligarch with close ties to the Russian president on Monday, the first in the government’s sanctions initiative to “seize and freeze” giant boats and other pricey assets of Russian elites.

Spain’s Civil Guard and American federal agents descended on the yacht at the Marina Real at the port of Palma de Mallorca, the capital of Spain’s Balearic Islands in the Mediterranean Sea. Associated Press reporters at the scene saw police going in and out of the boat on Monday morning.

The joint operation to seize the yacht, with Spain’s Civil Guard, the FBI, and Homeland Security Investigations, was carried out at the request of American authorities, the Civil Guard said.

A Civil Guard source told the Associated Press that the immobilized yacht is Tango, a 254-feet vessel that carries Cook Islands flag and that Superyachtfan.com, a specialized website that tracks the world’s largest and most exclusive recreational boats, values at $120 million. The source was also not authorized to be named in media reports and spoke to AP on condition of anonymity.

The yacht is among the assets linked to a billionaire and close ally of Vladimir Putin, Viktor Vekselberg, who heads the Moscow-based Renova Group, a conglomerate encompassing metals, mining, tech, and other assets, according to Treasury Department documents. All of Mr. Vekselberg’s assets in America are frozen and American companies are forbidden from doing business with him and his entities.

While Mr. Vekselberg has not been sanctioned by the European Union, he is under investigation in America for possible tax fraud, money laundering, and falsifying documents precisely to hide the ownership of the Tango, the Civil Guard said in a statement.

The move is the first time American government has seized an oligarch’s yacht since Attorney General Garland and the Treasury Secretary, Janet Yellen, assembled a task force known as REPO — short for Russian Elites, Proxies, and Oligarchs — as an effort to enforce sanctions after Russia invaded Ukraine in late February.

Mr. Vekselberg has long had ties to America, including a green card he once held and homes in New York and Connecticut. The Ukrainian-born businessman built his fortune by investing in the aluminum and oil industries in the post-Soviet era.

Mr. Vekselberg was also questioned in special counsel Robert Mueller’s investigation into Russian interference in the 2016 U.S. presidential election and has worked closely with his American cousin, Andrew Intrater, who heads the New York investment management firm Columbus Nova.

Messrs. Vekselberg and Intrater were thrust into the spotlight in the Mueller probe after the attorney for adult film star Stormy Daniels released a memo that claimed $500,000 in hush money was routed through Columbus Nova to a shell company set up by Donald Trump’s personal attorney, Michael Cohen. Columbus Nova denied that Mr. Vekselberg played any role in its payments to Cohen.

Mr. Vekselberg and Mr. Intrater met with Cohen at Trump Tower, one of several meetings between members of Trump’s inner circle and high-level Russians during the 2016 campaign and transition.

The 64-year-old mogul founded Renova Group more than three decades ago. The group holds the largest stake in United Co. Rusal, Russia’s biggest aluminum producer, among other investments.

Mr. Vekselberg was first sanctioned by America in 2018, and again in March of this year, shortly after the invasion of Ukraine began. Mr. Vekselberg has also been sanctioned by authorities in the United Kingdom.

The yacht sails under Cook Islands flag and is owned by a company registered in the British Virgin Islands administered by different societies in Panama, the Civil Guard said, “following a complicated financial and societal web to conceal its truthful ownership.”

Agents confiscated documents and computers inside the yacht that will be analyzed to confirm the real identity of the owner, it said.

The Justice Department has also launched a sanctions enforcement task force known as KleptoCapture, which also aims to enforce financial restrictions in America imposed on Russia and its billionaires, working with the FBI, Treasury, and other federal agencies. That task force will also target financial institutions and entities that have helped oligarchs move money to dodge sanctions.

The White House has said that many allied countries, including German, the U.K, France, Italy, and others are involved in trying to collect and share information against Russians targeted for sanctions. 

In his State of the Union address, President Biden warned oligarch that America and European allies would “find and seize your yachts, your luxury apartments, your private jets.”

“We are coming for your ill-begotten gains,” he said.

Monday’s capture is not the first time Spanish authorities have been involved in the seizure of a Russian oligarch’s superyacht. Officials there said they had seized a vessel valued at over $140 million owned by the CEO of a state-owned defense conglomerate and a close Putin ally.

French authorities have also seized superyachts, including one believed to belong to a Putin ally,  Igor Sechin, who runs Russian oil giant Rosneft, which has been on the American sanctions list since Russia annexed Crimea in 2014.

Italy has also seized several yachts and other assets.

Italian financial police moved quickly seizing the superyacht Lena belonging to an oligarch close to Mr. Putin, Gennady Timchenko, in the port of San Remo; the 215-foot Lady M owned by Alexei Mordashov in nearby Imperia, featuring six suites and estimated to be worth 65 million euros; as well as villas in Tuscany and Como, according to government officials.