WASHINGTON — The U.S. sought to punish Russia on Monday for interfering with the November 2018 midterm elections by placing the yacht and private planes of a Russian financier on an international sanctions list along with employees of the Internet Research Agency that he has funded to spread false information on social media.

Sanctions placed on the planes and yacht of financier Yevgeny Prigozhin mean that U.S. and many foreign ports would face penalties for transactions involving the vessel or aircraft, according to a U.S. Treasury Department notice announcing the measures.

Prigozhin, who was already on the sanctions list for his alleged involvement in influencing the 2016 U.S. elections, uses a series of front companies to manage the yacht and planes that he and his family use to vacation around the world, Treasury said.

The U.S. accuses him of attempting to “subvert American democratic processes,” though there is no evidence that the efforts of the Internet Research Agency or other foreign actors managed to prevented anyone from voting, changed votes or disrupted the counting, Treasury Secretary Steven Mnuchin said.

“Let this serve as a warning: any actors who continue to engage with these individuals, companies, aircraft or vessel may also be subject to future sanctions,” Secretary of State Mike Pompeo said in a statement. “We have been clear: We will not tolerate foreign interference in our elections.”

The U.S. is also taking measures to protect the 2020 elections against adversaries that may be seeking to influence that vote as well, Treasury said, singling out Russia, Iran and China.

In the run up to the November 2018 elections, the Internet Recent Agency, based in St. Petersburg, Russia, used fake social media accounts to flood America with disinformation aimed to discredit candidates it deemed hostile to Russia. In 2016, the same organization sought to help Donald Trump by disparaging Hillary Clinton, according to the special counsel Robert Mueller’s report on Russian interference in the campaign.