WASHINGTON — The Russian government undertook a "sweeping and systematic" campaign to help Donald Trump win the White House in 2016, believing it would benefit from his presidency, and found campaign aides eager to benefit from their help, special counsel Robert Mueller concluded in a report released Thursday.

The investigation did not find that the president or his campaign conspired with Russia to win the election. But the special counsel's report revealed a detailed portrait of a campaign that was receptive to Russia's efforts, was eager to benefit from them, and did not appear to appreciate the massive foreign intelligence operation behind those activities.

"The investigation established multiple links between Trump campaign officials and individuals tied to the Russian government," the more than 400-page report says.

Those links included Trump's business interests in Moscow, communications between Russia-affiliated individuals and Trump advisers and aides and offers of assistance to the campaign. In some instances, the campaign welcomed the offers; in others, they shied away. But ultimately, the evidence the special counsel's office had amassed over two years of investigation "did not establish" a conspiracy, the report says.

The report details several instances, some as early as 2015, in which Trump associates and surrogates appeared to teeter toward conspiracy, but ultimately did not cross the line into committing a crime.

The earliest contacts happened in 2015, when Trump, then a candidate, signed a letter of intent for a potentially lucrative Trump Tower project in Moscow. Trump's personal lawyer, Michael Cohen, handled the project's negotiations that stretched well into 2016, even as Trump publicly denied having any business interests in Russia.

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In November 2015, Felix Sater, a New York real-estate developer who had explored the possibility of a Trump Tower in Moscow, told Cohen in an email that the project could help Trump win the presidency and that Sater would get Russian President Vladimir Putin's team to "buy in" on it.

"Buddy our boy can become President of the USA and we can engineer it ... Michael, Putin gets on stage with Donald for a ribbon cutting for Trump Moscow, and Donald owns the republican nomination," Sater wrote, according to the report. "That the game changer."

The project did not come to fruition. Cohen later said that he did not consider the political consequences of a Trump Tower Moscow and that he did not recall Trump or members of his campaign discussing the subject, the report says.

Other encounters between Trump's aides and people tied to Russia were more closely related to the election.

In perhaps the best-known example, Trump aides including his eldest son, Donald Trump Jr., met with a Russian lawyer who had promised damaging information about Trump's Democratic rival, Hillary Clinton. Trump Jr. enthusiastically accepted the meeting, after he was told the session was the idea of the "crown prosecutor of Russia," the report says.

Mueller's team looked into whether that meeting violated federal election laws barring contributions from foreign nations. But prosecutors ultimately decided they could not meet the high burden of proof because of questions about whether Trump's associates acted "willfully." Prosecutors also concluded that it would be difficult to prove beyond a reasonable doubt that the value of the promised information about Clinton exceeded the threshold for a criminal violation.

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Further, the campaign showed interest in WikiLeaks' release of damaging documents and emails stolen from Clinton and the Democratic Party. Prosecutors said the anti-secrecy group obtained the stolen emails from Russia's military intelligence service, which hacked Democratic political organizations.

On July 27, 2016, then-candidate Trump publicly implored Russia to find 30,000 emails that had been deleted from a private server Clinton used while she was secretary of State. Within five hours of that request, the report says, Russian hackers sought to break in to several email accounts, including one belonging to a Clinton aide. After he became president, Trump repeatedly directed then-national security adviser Michael Flynn to find the missing emails, and Flynn subsequently contacted multiple people who spent months trying to do that — but to no avail, the report says.

One of these people drafted multiple emails claiming he was in contact with Russian hackers, but the special counsel's investigation did not find evidence that contacts or meetings with Russian hackers occurred, the report says.

Investigators wrote that Russia leaked stolen emails to WikiLeaks because it knew the anti-secrecy organization opposed a Clinton presidency.

"We are ready to support you. We have some sensitive information too, in particular, her financial documents. Let's do it together," according to a message the Russians sent to WikiLeaks in June 2016.

The report also showed communications between WikiLeaks and the president's eldest son weeks before the presidential election and around the same time the anti-secrecy website published troves of damaging campaign emails from the Clinton camp.

On Oct. 3, 2016, WikiLeaks sent a message to Trump Jr. asking for help to disseminate a link alleging Clinton had advocated using a drone to target Julian Assange, WikiLeaks' founder.

"Had done so," Trump Jr. responded.

"What's behind this Wednesday leak I keep reading about?" Trump Jr. asked. WikiLeaks didn't respond.

On Oct. 12, 2016, after WikiLeaks released the Clinton emails, it wrote to Trump Jr. again.

"Great to see you and your dad talking about our publications. Strongly suggest your dad tweets this link if he mentions us," WikiLeaks wrote, including a link it says would help in "digging through" the leaked emails.

The contact that first aroused the FBI's suspicion was an interaction between Trump adviser George Papadopoulos and a foreign diplomat. Prosecutors said Papadopolous boasted that he had been told that Russia had gathered damaging information on Clinton in the form of thousands of emails. Mueller's report said Papadopoulos conveyed that "the Trump Campaign had received indications from the Russian government that it could assist the Campaign through the anonymous release of information."

Ultimately, however, the special counsel's investigation did not find evidence that these contacts were part of a coordinated effort between Russia and the Trump campaign to influence the election. The investigation also did not yield enough evidence that any Trump campaign official acted as a foreign agent "subject to the direction or control" of the Russian government, which would have required them to register with the federal government.

Matthew Jacobs, a former federal prosecutor who worked for Mueller when he was U.S. attorney in San Francisco, said the decision to not charge anyone with conspiracy stems from a "very narrow" interpretation of the law.

"They're the ones who are benefiting," Jacob, a white-collar defense attorney, said of the Trump campaign. He added: "If you and I get together and we talk about robbing a bank and I say, it would be really great if you rob a bank, and you rob a bank and you share the proceeds with me, then I've participated in the conspiracy."

Trump Jr. on Thursday took to Twitter to claim vindication: "TOLD YA!!!"

In written responses to the special counsel's written questions during the investigation, Trump, on multiple occasions, claimed that he did not remember some of the episodes investigators detailed. Trump told Mueller and his team that he had no recollection that the Trump Tower meeting involved Russians. He also said that he did not recall being told about WikiLeaks possession of Clinton emails before they were leaked.

Mueller's investigation revealed a large-scale Russian operation that used two methods to influence the U.S. election: a hacking operation targeting the Clinton campaign and a disinformation and social media effort to sow chaos in the political arena.

The inquiry, which began in secret when the FBI began looking into Trump's campaign aides months before the election, led to the indictment of 12 Russian nationals for hacking Democratic computers. Mueller also indicted 13 other Russian nationals, some with ties to Russian President Vladimir Putin, and three entities for meddling in the election.

The report also described a massive online campaign that began as early as 2014, with the goal of spreading distrust in the American political system. At the center of this operation is a Russian firm called Internet Research Agency, operating out of St. Petersburg. Its staff was in the hundreds and its annual budget soared to the equivalent of millions of dollars.

Aside from hacking the Clinton campaign, Russian intelligence officials also went after federal, state and local individuals and organizations administering elections, the report says. They targeted technology firms responsible for making and maintaining voter-registration software and electronic polling stations.

Russians posed as Americans, using stolen identities as they attempted to coordinate with members of the Trump campaign. They staged dozens of rallies that supported Trump and disparaged Clinton at several key states. They created thousands of fake social media accounts and groups that targeted divisive issues, supported Trump and disparaged Clinton. The accounts attracted hundreds of thousands of followers — and were cited or retweeted by several Trump campaign officials and surrogates, including Trump Jr., Eric Trump, Kellyanne Conway and Flynn, who peddled voter fraud allegations and accusations that Clinton mishandled classified information as secretary of State.

Mueller's team of 19 lawyers conducted a massive investigation, issuing more than 2,800 subpoenas, executing nearly 500 search warrants and interviewing about 500 witnesses.

Contributing: John Kelly, Ledyard King, Gregory Korte, Kevin McCoy, Steve Reilly and Deirdre Shesgreen