U.S. moves to seize 2 planes believed to belong to Roman Abramovich.

Federal authorities intend to seize two aircraft believed to be owned by Roman Abramovich, saying that the Russian oligarch violated strict U.S. export regulations linked to Russia’s invasion of Ukraine, according to court filings.

The planes — a Boeing 787 Dreamliner and a Gulfstream jet — are both manufactured in the United States and valued at over $400 million.

In March, a few weeks after Russia invaded Ukraine, Mr. Abramovich had the planes flown to Russia, and in one case to another country, without securing the necessary licenses or approval from the Bureau of Industry and Security, a unit of the Department of Commerce, the filings said. The Boeing was flown to the United Arab Emirates and the Gulfstream to Russia.

Agents with the F.B.I. traced the aircraft to Mr. Abramovich, who owns them though a series of shell companies in the British Virgin Islands, Cyprus and Isle of Jersey, according to an affidavit submitted in federal court in Manhattan in support of the seizure warrants.

Representatives for Mr. Abramovich did not return requests for comment.

These moves stem from a new Department of Justice initiative, known as Task Force KleptoCapture, which was established in March to go after assets belonging to Russian oligarchs.

It’s the first time the task force has taken action against Mr. Abramovich, who is believed to be one of Russia’s wealthiest industrialists with an estimated net worth in excess of $13 billion. Mr. Abramovich, the former longtime owner of the Chelsea Football Club in London, has been sanctioned by the United Kingdom and the European Union, but not by the United States.

American officials have held off on formally placing sanctions on Mr. Abramovich partly because he has served as an intermediary in negotiations between Ukraine and Russia. But the effort to seize assets believed to belong to Mr. Abramovich indicates that federal authorities are willing to pursue actions against any wealthy individual who is found to have violated U.S. laws and regulations.

In conjunction with the task force’s action, the Commerce Department announced it had filed administrative charges against Mr. Abramovich for violating the export control regulations. In early March, after the invasion of Ukraine, the Commerce Department made it all but impossible for any aircraft manufactured in the United States to get a license to be moved to Russia.

Mr. Abramovich’s vast wealth includes billions invested in dozens of offshore funds managed by hedge funds in the United States. Those accounts, many of which are in the Cayman Islands or Jersey, have been frozen because of British sanctions. Just as he did with his aircraft, Mr. Abramovich used a series of shell companies in the British Virgin Islands, Cyprus and Jersey to invest with hedge funds.

The kleptocapture task force has already moved to seize yachts owned by other oligarchs who have been sanctioned by the United States. Mr. Abramovich is believed to own at least five yachts, but none of his vessels have been seized by the United States.

The seizing of assets is the just the first step in a long process called civil forfeiture, which requires prosecutors to prove in federal court that the assets were bought with the illicit proceeds of a crime. Only then can the federal government take permanent possession of them.