Russia Sought to Assassinate an Informant in the U.S.

Mr. Fuentes and his wife were told to leave, but security cameras captured the incident. Two days later, he tried to fly to Mexico, but U.S. Customs and Border Protection officers stopped him and searched his phone, discovering the picture of Mr. Poteyev’s vehicle.

After he was arrested, Mr. Fuentes provided details of the plan to American investigators. He believed the Russian official he had been meeting worked for the F.S.B., Russia’s internal security service. But covert operations overseas are usually run by the S.V.R., which succeeded the K.G.B., or the G.R.U., Russia’s military intelligence agency.

One of the former officials said Mr. Fuentes, unaware of the target’s significance, was merely gathering information for the Russians to use later.

Mr. Fuentes’s lawyer, Ronald Gainor, declined to comment.

The plot, along with other Russian activities, elicited a harsh response from the U.S. government. In April 2021, the United States imposed sanctions and expelled 10 Russian diplomats, including the chief of station for the S.V.R., who was based in Washington and had two years left on his tour, two former American officials said. Throwing out the chief of station can be incredibly disruptive to intelligence operations, and agency officials suspected that Russia was likely to seek reprisal on its American counterpart in Moscow, who had only weeks left in that role, the officials said.

“We cannot allow a foreign power to interfere in our democratic process with impunity,” President Biden said at the White House in announcing the penalties. He made no mention of the plot involving Mr. Fuentes.

Sure enough, Russia banished 10 American diplomats, including the C.I.A.’s chief of station in Moscow.

Adam Entous contributed reporting.