WASHINGTON — President Vladimir V. Putin of Russia authorized extensive efforts to hurt the candidacy of Joseph R. Biden Jr. during the election last year, including by mounting covert operations to influence people close to President Donald J. Trump, according to a declassified intelligence report released on Tuesday.
The report did not name those people but seemed to refer to the work of Mr. Trump’s former personal lawyer Rudolph W. Giuliani, who relentlessly pushed accusations of corruption about Mr. Biden and his family involving Ukraine.
“Russian state and proxy actors who all serve the Kremlin’s interests worked to affect U.S. public perceptions,” the report said.
The declassified report represented the most comprehensive intelligence assessment of foreign efforts to influence the 2020 vote. Besides Russia, Iran and other countries also sought to sway the election, the report said. China considered its own efforts but ultimately concluded that they would fail and most likely backfire, intelligence officials concluded.
A companion report by the Justice and Homeland Security Departments also rejected false accusations promoted by Mr. Trump’s allies in the weeks after the vote that Venezuela or other countries had defrauded the election.
The reports, compiled by career officials, amounted to a repudiation of Mr. Trump, his allies and some of his top administration officials. They reaffirmed the intelligence agencies’ conclusions about Russia’s interference in 2016 on behalf of Mr. Trump and said that the Kremlin favored his re-election. And they categorically dismissed allegations of foreign-fed voter fraud, cast doubt on Republican accusations of Chinese intervention on behalf of Democrats and undermined claims that Mr. Trump and his allies had spread about the Biden family’s work in Ukraine.
The report also found that neither Russia nor other countries tried to change ballots themselves. Efforts by Russian hackers to gain access to state and local networks were unrelated to efforts by Moscow to influence the presidential vote.
The declassified report did not explain how the intelligence community had reached its conclusions about Russian operations during the 2020 election. But the officials said they had high confidence in their conclusions about Mr. Putin’s involvement, suggesting that the intelligence agencies have developed new ways of gathering information after the extraction of one of their best Kremlin sources in 2017.
Foreign efforts to influence United States elections are likely to continue in coming years, American officials said. The public has become more aware of disinformation efforts, and social media companies act faster to take down fake accounts that spread falsehoods. But a large number of Americans remain open to conspiracy theories pushed by Russia and other adversaries, a circumstance that they will exploit, officials warned.
“Foreign malign influence is an enduring challenge facing our country,” Avril D. Haines, the director of national intelligence, said in a statement. “These efforts by U.S. adversaries seek to exacerbate divisions and undermine confidence in our democratic institutions.”
While it was declassified by the Biden administration, the report is based on work done during the Trump administration, according to intelligence officials, reflecting the vastly different views that officers had from their political overseers, who were appointed by Mr. Trump.
The report rebutted yearslong efforts by Mr. Trump and his allies to sow doubts about the intelligence agency’s assessments that Russia not only wanted to sow chaos in the United States but also favored his re-election.
“They were disingenuous in downplaying Russia’s influence operations on behalf of the former president,” Representative Adam B. Schiff, Democrat of California, who leads the House Intelligence Committee, said in an interview. “It was a disservice not to level with the public and to try to fudge the intelligence in the way they did.”
Some of the report’s details were released in the months leading up to the election, reflecting an effort by the intelligence community to disclose more information about foreign operations during the campaign after its reluctance to do so in 2016 helped misinformation spread.
During the 2020 campaign, intelligence officials outlined how Russia was spreading damaging information about Mr. Biden’s son, Hunter Biden, in an attempt to bolster Mr. Trump’s re-election chances. It also outlined efforts by Iran in the final days before the election to aid Mr. Biden by spreading letters falsely purporting to be from the Proud Boys, a far-right group.
Accusations of election interference have been some of the most politically divisive in recent years. The intelligence report is akin to a declassified assessment in early 2017 that laid out the conclusions about Russia’s efforts in Mr. Trump’s electoral victory, further entrenched the partisan debate over his relationship with Moscow and cemented his enmity toward intelligence and law enforcement officials.
With Mr. Trump out of office and the new report’s conclusions largely made public in releases during the campaign, the findings were not expected to prompt as much partisan fury. But elements of the report are likely to be the subject of political fights.
Its assessment that China sat on the sidelines is at odds with what some Republican officials have said. In private briefings on Capitol Hill, John Ratcliffe, Mr. Trump’s last director of national intelligence, said Chinese interference was a greater threat in 2020 than Russian operations.
The declassified documents released on Tuesday included a dissenting minority view from the national intelligence officer for cyber that suggested that the consensus of the intelligence community was underplaying the threat from China.
In a letter in January, Mr. Ratcliffe wrote in support of that minority view and said that the report’s main conclusions about China “fell well short of the mark.” He said the minority conclusion was more than one analyst’s view and argued that some intelligence officials were hesitant to label Chinese actions as influence or interference.
Privately, some officials defended the consensus view, saying their reading of the intelligence supported the conclusions that China sought some level of influence but avoided any direct efforts to interfere in the vote.
The most detailed material in the assessment was about Russia, which sought to influence how the American public saw the two major candidates “as well as advance Moscow’s longstanding goals of undermining confidence in U.S. election processes.”
Moscow used Andriy Derkach, a pro-Russian member of Ukraine’s Parliament, to undermine Mr. Biden, the report confirmed. Mr. Derkach released leaked phone calls four times to undermine Mr. Biden and link him to Ukrainian corruption. The report said Mr. Putin “had purview” over the actions of Mr. Derkach, who had ties to Russian intelligence.
Citing in one instance a meeting between Mr. Derkach and Mr. Giuliani, intelligence officials warned Mr. Trump in 2019 that Russian intelligence officers were using his personal lawyer as a conduit for misinformation.
Mr. Giuliani also provided materials from Ukraine to American investigators to push for federal inquiries into Mr. Biden’s family, a type of operation that the report mentioned as an example of Russia’s covert efforts without providing names or other identifying details.
The report also named Konstantin V. Kilimnik, a former colleague of Mr. Trump’s onetime campaign manager Paul Manafort, as a Russian influence agent. Mr. Kilimnik took steps throughout the 2020 election cycle to hurt Mr. Biden and his candidacy, the report said, helping pushed a false narrative that Ukraine, not Russia, was responsible for interfering in American politics.
During the 2016 campaign, Mr. Manafort shared inside information about the presidential race with Mr. Kilimnik and the Russian and Ukrainian oligarchs whom he served, according to a bipartisan report last year by the Senate Intelligence Committee.
“Kilimnik was back at it again, along with others like Derkach,” Mr. Schiff said. “And they had other conduits for their laundered misinformation, including people like Rudy Giuliani.”
Neither Mr. Giuliani nor his representatives returned a request for comment.
Collecting intelligence to feed to Mr. Trump’s allies and use against Mr. Biden was a priority for Russian intelligence. Moscow’s military intelligence unit, the G.R.U., conducted a hacking campaign against a Ukrainian energy firm, Burisma, in what was most likely an attempt to gather information about Mr. Biden’s family and their work for the company, the report confirmed.
In the closing weeks of the campaign, intelligence officials also said that Russian hackers had broken into state and local computer networks. But the new report said those efforts were not aimed at changing votes.
Unmentioned in this report was the wide-ranging hacking of federal computer systems using a vulnerability in software made by SolarWinds. The absence of a concerted effort by Russia to change votes suggests that Moscow had refocused its intelligence service on a broader effort to attack the U.S. government.
Earlier in 2020, American officials thought Iran was likely to stay on the sidelines of the presidential contest. But Iranian hackers did try a last-minute effort to change the vote in Florida and other states.
Iranian hackers sent “threatening, spoofed emails” to Democratic voters that purported to be from the Proud Boys, the report said. The group demanded that the recipients change their party affiliation and vote for Mr. Trump. They also pushed a video that supposedly demonstrated voter fraud.
The Iranian effort essentially employed reverse psychology. Officials said Iranian operatives hoped the emails would have the opposite effect of the message’s warning, rallying people to vote for Mr. Biden by thinking Mr. Trump’s supporters were playing dirty campaign tricks. Ayatollah Ali Khamenei, Iran’s supreme leader, authorized the campaign, the report said.