The assessment found that Russian Federation was seeking to "denigrate" Mr Biden.
"China sought stability in its relationship with the United States and did not view either election outcome as being advantageous enough for China to risk blowback if caught", it said.
The Russians were responsible for 'denigrating President Biden's candidacy and the Democratic Party, supporting former President Trump, undermining public confidence in the electoral process, and exacerbating sociopolitical divisions in the US,' the report said, according to CNN. "No mention in headline or framing of the report's finding on Iran's attempts to interfere in the 2020 election with the goal of hurting Trump's reelection chances".
Asked about the report, a Biden administration official, requesting anonymity, said the president had "been clear" that the United States would respond to destablising Russian actions.
Unlike their findings regarding Russia's 2016 election interference, the intelligence community found no effort by the country's military to access USA election infrastructure, but the report said the influence operations remained a common thread.
Intelligence experts also found that China, which was previously thought to be expanding its USA influence efforts, ultimately did not deploy operations to affect the outcome of the election.
Overall, the report released by the Office of the Director of National Intelligence provides the most comprehensive assessment of foreign threats to the 2020 elections to date, detailing extensive influence operations by United States adversaries, including Russian Federation and Iran, that sought to undermine confidence in the democratic process, in addition to targeting specific presidential candidates.
USA election officials have repeatedly described last year's balloting as secure and free of fraud.
Despite those threats, though, intelligence officials found "no indications that any foreign actor attempted to interfere in the 2020 USA elections by altering any technical aspect of the voting process, including voter registration, ballot casting, vote tabulation, or reporting results".
Russian Federation also featured prominently in the report, having undertaken an even larger effort.
The report wades into the politically freighted assessments of ferreting out which foreign adversaries supported which candidates during the 2020 presidential election. But the new report said those efforts were not aimed at changing votes.
Tehran and Moscow have previously denied any involvement in attempting to influence U.S. elections.
The report said Mr. Putin had purview over operations including the activities of Andriy Derkach, a Ukrainian lawmaker sanctioned by the U.S. Treasury Department in September, and Konstantin Kilimnik, whom the U.S. Senate Intelligence Committee identified as a Russian intelligence officer. It said Kilimnik and Derkach met and gave materials to Trump-linked people to push for formal investigations, and Derkach released four audio recordings seeking to suggest Biden tried to protect his son Hunter from a corruption probe in Ukraine.
Tuesday's report, however, says China ultimately did not interfere on either side and "considered but did not deploy" influence operations meant to affect the outcome.
"These efforts by USA adversaries seek to exacerbate divisions and undermine confidence in our democratic institutions", Haines wrote in a statement. But it mostly backtracked on another key pronouncement that China "prefer" former President Donald Trump lose, saying instead that China "considered but did not deploy influence efforts".
While foreign disinformation and interference was a major concern heading into the 2020 campaign, domestic efforts to disrupt the race - including by then-President Donald Trump and his allies - turned out to be of far greater significance.
Iranian Supreme Leader Ali Khamenei likely approved Tehran's effort to sway the 2020 presidential election in the United States, according to "high-confidence" U.S. intelligence report released today. The Iranian cyber campaign relied on cheap, scalable methods that didn't require physical access to the US, the report found.