Russia has covertly spent more than $300 million since 2014 on efforts to influence politicians and other officials in more than two dozen countries, the U.S. State Department alleged on September 13.
The money was spent to support think tanks backed by far-right nationalist political parties and on such things as front organizations used to funnel money to preferred causes or politicians.
U.S. intelligence believes $300 million is a "minimum" estimate and that Russia likely has transferred additional funds in cases that have gone undetected, an official who briefed reporters said.
"We think this is just the tip of the iceberg, and we are engaging with allies and partners to gather more information about this threat," the official said.
U.S. diplomats were sharing their findings with governments in more than 100 nations.
The information follows a review by the U.S. intelligence community of Russia's efforts to influence other countries' politics, the official said.
The State Department is publicly providing some information from the review because of an expectation that Russia would "increasingly rely on its covert influence toolkit" in the coming months, they said.
The report does not name specific Russian targets but says Moscow likely will increasingly turn to covert political financing to undermine international sanctions over its war in Ukraine.
The official noted that President Joe Biden had recently extended a national emergency declaration addressing the continued threat of foreign election interference.
The Russian Embassy in Washington did not immediately respond to RFE/RL’s request for comment.
The official, who briefed reporters on condition of anonymity, did not provide specific evidence about the alleged secret financing. U.S. officials previously have pointed to Bosnia-Herzegovina and Ecuador as countries where Russia has intervened directly through its financial power.
State-owned Russian companies have directly funneled covert funding in Central America, Asia, the Middle East, and North Africa, the assessment said. Russia has used cash, made payments in cryptocurrencies, and sent "lavish" gifts, the assessment said.
The Biden administration requested the assessment following Russia's invasion of Ukraine, which prompted international sanctions in an effort to isolate Moscow.
The official also declined to say how much money Russia is believed to have spent in Ukraine, where President Volodymyr Zelenskiy and his top deputies have long accused Russian President Vladimir Putin of meddling in domestic politics.
The official rejected comparisons between Russia's activities and U.S. financing of media and political initiatives.
The official said the difference was that Putin had spent huge sums “in an attempt to manipulate democracies from the inside.”