A Republican-led Senate panel has concluded that Trump campaign connections with Russia in 2016"represented a grave counterintelligence threat".
It is the fifth and probably final report into Russian meddling throughout the 2016 presidential election.
When asked about the report on Tuesday, Mr. Trump said he "did not read it".
It details the connections between Trump campaign staff and Russian operatives, such as a Kremlin intelligence officer.
The findings also confirm aspects of the special counsel Robert Mueller's report from his criminal probe to the Trump effort and Russian election hindrance.
What's in the report?
The bipartisan senate committee investigation was not a criminal inquiry, but was supposed to supply recommendations to prevent future interference.
The report concluded that the Kremlin "engaged in an aggressive, multifaceted effort to influence, or attempt to influence" the 2016 election, and that some Trump partners were keen on aid from Russia.
It said the Trump campaign, with many affiliates who had no government experience, were easy targets for foreign influence.
The committee also highlighted the role of former Trump campaign manager Paul Manafort, that had been convicted of conspiracy and fraud charges during the Mueller inquiry.
Manafort's contact with Russian oligarchs and intellect affiliates - specifically Konstantin Kilimnik- along with his accessibility to Mr. Trump "created opportunities for Russian intelligence services to exert influence over, and also acquire confidential information on, the Trump Campaign," the committee alleges.
The committee also reported that Russian President Vladimir Putin was behind the WikiLeaks attempt to hack Democratic Party officials and leak information to damage Hillary Clinton's campaign.
The report confirmed the Kremlin used Manafort and WikiLeaks to assist Mr. Trump win the 2016 election, and that WikiLeaks was aware that it had been helping Russian intelligence.
All you Want to know about Trump Russia narrative
Additionally, it found the Trump campaign attempted to obtain information concerning the flow from Roger Stone - a longtime Trump ally and adviser. The committee wasn't able to ascertain how much access Stone had to WikiLeaks, however.
Mr. Trump has said he does not remember speaking about WikiLeaks with Stone, but Tuesday's report found that "despite Trump's recollection" he did talk to Stone along with other campaign staff about the matter" on several occasions".
Stone was convicted of lying to Congress, obstruction and witness tampering, but pardoned by Mr. Trump in July.
The president has long derided asserts that his election victory was influenced by Russia, occasionally questioning findings from his very own bureaus.
In response to a question about the report, Mr. Trump told reporters: "I really don't know anything about it.
He added: "It's all a hoax."
White House spokesman Judd Deere, however, said the report was further confirmation that "there was absolutely no collusion between the Trump effort and Russia".