US Attorney Damian Williams said in a release on Monday that his office was using every legal tool available to respond to "Russian's illegal war in Ukraine".
"Our international partners — nations devoted to the rule of law — far outnumber those jurisdictions where these aircraft can safely hide, and our investigation of illegal exports in violation of US law will continue unabated," he said.
Matthew S Axelrod, assistant secretary of commerce for export enforcement, said the US Commerce Department had made recent changes to keep its enforcement actions public regarding unprecedented export controls stemming from the invasion of Ukraine.
He said the action "provides notice to the world of our commitment to enforcing those controls aggressively in a transparent way."
Andrew Adams, a prosecutor who heads the unit pursuing the assets of Russian oligarchs, said the public nature of Monday's action is meant to remind "members of the aviation, insurance, and financial industries that these aircraft constitute tainted property under active investigation by the United States."
Justice Department officials say they have received strong support from companies and organisations and from countries that in the past had been viewed as safe havens for parking illegal assets.
Abramovich, who recently sold his stake in Chelsea, a Premier League football club in London, is among the wealthier Russians whose assets are being watched for sanctions violations after the Ukraine invasion.
In explaining the move to seize the planes, an FBI agent wrote in an affidavit that the Boeing 787-8 Dreamliner aircraft and the Gulfstream G650ER plane are subject to seizure because they have been moved between March 4 and March 15 without licences being obtained in violation of sanctions placed against Russia.
According to the affidavit, Abramovich controlled the Gulfstream through a series of shell companies. The plane, it said, is believed to have been in Moscow since March 15.
The Boeing, meanwhile, is believed to be in Dubai, in the United Arab Emirates, following a round-trip March 4 flight from Dubai to Moscow, the affidavit said.