The former campaign chairman Paul Manafort kept in close touch with a longtime colleague whom Senate investigators identified as a Russian intelligence officer.
Russian intelligence services pursued myriad avenues to influence the Trump campaign in 2016, according to the Senate Intelligence Committee, but none was more important than the relationship between the campaign chairman Paul Manafort and a man who had been his friend and co-worker for years: a Russian intelligence officer named Konstantin V. Kilimnik. Their link was “the single most direct tie between senior Trump campaign officials and the Russian intelligence services,” according to the fifth and final volume of the committee’s report on its bipartisan three-year investigation issued Tuesday. While the interactions between the two men remain largely hidden, investigators found enough facts to declare that Mr. Manafort created “a grave counterintelligence threat” by sharing inside information about the presidential race with Mr. Kilimnik and the Russian and Ukrainian oligarchs whom he served. The report portrayed Mr. Manafort as deeply compromised by years of business dealings with those oligarchs. Collectively, they had paid him tens of millions of dollars, lent him millions more and may also have owed him millions. These complex financial entanglements apparently figured in Mr. Manafort’s decision to give Mr. Kilimnik inside campaign information, including confidential polling data and details of Mr. Trump’s campaign strategy. The report builds on other evidence suggesting that Mr. Manafort hoped that Mr. Kilimnik would open up lucrative business deals with the oligarchs in return or that they would consider the value of the information as its own form of payment. The committee had little explanation for the connection between the two men, citing Mr. Manafort’s lies to federal authorities, coupled with the care the two men took to protect their communications, as roadblocks to learning more. “What did the Russians do with all this information, how did they use it, did they use it?” Senator Mark Warner of Virginia, the committee’s top Democrat, asked in an interview on Tuesday. “Those are serious counterintelligence questions we may never get the full answer on.” The report said Mr. Kilimnik was Mr. Manafort’s link to Oleg V. Deripaska, a Russian oligarch who is close to President Vladimir V. Putin of Russia and has acted “as a proxy for the Russian state and intelligence services” since at least 2004, when Mr.
