After years of painstaking surveillance, the F.B.I. did not want any of its targets to escape, and “you can’t take down one without taking down all of them,” one law enforcement official said.

The F.B.I. on Sunday arrested 10 people in Yonkers, Manhattan, New Jersey, Boston and Virginia and charged them with conspiracy to act as an unregistered agent of a foreign government. Most were also charged with conspiracy to commit money laundering.

American officials said they believed that most of the accused spies had been born in Russia and had been given sophisticated training before resettling in the United States, posing as married couples. They connected with various Americans of influence or knowledge, including a “prominent New York-based financier” described as a political fund-raiser with personal ties to a cabinet official, a former high-ranking national security official, and a nuclear weapons expert.

Image Former President Bill Clinton held discussions with Prime Minister Vladimir V. Putin of Russia on Tuesday outside Moscow. Credit... Alexey Druginyn/RIA Novosti, via European Pressphoto Agency

But they were instructed not to seek government jobs, because spy bosses in Moscow thought their cover stories would not stand up under a serious background investigation. So they were assigned to feed to Moscow what amounted to briefing papers on economics issues, American government players and diplomatic and military affairs.

One, the agent known as Cynthia Murphy, talked to New York contacts and reported on “prospects for the global gold market” that her bosses (whose spelling in English-language messages was imperfect) told her were “v. usefull” and passed to the Russian Ministry of Finance.

Before a visit to Moscow by President Obama last year, Ms. Murphy and her ostensible husband, Mr. Murphy, were instructed to size up American intentions from their home in Montclair, N.J. “Try to outline their views and most important Obama’s goals which he expects to achieve during summit in July and how does his team plan to do it (arguments, provisions, means of persuasion to ‘lure’ [Russia] into cooperation in US interests),” the spy bosses in Moscow asked, according to the charging papers.