The mystery surrounding the meetings seems to have drawn attention from the special counsel, Robert Mueller, who is examining ties between the President and Russia. And it has generated a furor in Congress, where Democrats are pushing to subpoena the notes of the President's interpreters or perhaps the interpreters themselves. Veterans of past administrations could not recall a precedent for a president meeting alone with an adversary and preventing his own advisers from being briefed on what was said. When they meet with foreign leaders, presidents typically want at least one aide in the room – not just an interpreter – to avoid misunderstandings later. Clockwise from top-left: Trump and Putin in Hamburg, Germany, where they had two meetings; in Da Nang, Vietnam during an APEC summit; their first formal meeting in Helsinki, Finland, at the G20 meeting in Buenos Aires. Credit:AP "All five of the presidents whom I worked for, Republicans and Democrats, wanted a word-for-word set of notes, if only to protect the integrity of the American side of the conversation against later manipulation by the Soviets or the Russians," said Victoria J. Nuland, a career diplomat who worked for Dick Cheney and Hillary Clinton, among others. That would seem an even greater imperative for Trump, who knew there were questions about his relationship with Putin given that US intelligence agencies concluded that Moscow tried to help elect him.

"If any president would have wanted witnesses and protection, it ought to have been Donald Trump," said Richard N. Haass, the president of the Council on Foreign Relations and adviser to four presidents, most recently as President George W. Bush's State Department policy planning director. "And yet he chose not to, and that adds fuel to the fire that something here is not right." Trump's defenders acknowledge his approach does not resemble the way his predecessors operated, but note that he has been an unorthodox president in so many ways that it does not prove anything untoward. And, they say, he has reason to feel burned since previous interactions with foreign leaders have leaked, including full transcripts of telephone calls with the leaders of Mexico and Australia published in The Washington Post. "Of course I was disappointed with Helsinki, but I do not just look at how the President handles specific meetings with Putin," said Luke Coffey, a foreign policy scholar at the Heritage Foundation. "Instead, I'm most interested in what the actual policies are coming out of the administration." He cited additional sanctions, weapons sent to Ukraine, increased Pentagon spending meant to counter Russian aggression and opposition to a new Russian pipeline to Europe. All that, he said, "is proof that this is one of the toughest administrations on Russia since Reagan." The question of Trump's meetings with Putin was revived by a pair of news stories last weekend. The New York Times reported that after Trump fired FBI Director James B. Comey in 2017, the bureau opened a counterintelligence investigation to explore whether the President was acting on Russia's behalf. The Post reported that Trump had gone to unusual lengths to conceal details of his talks with Putin, including taking his interpreter's notes.

The White House dismissed the stories as unfair smears. "The liberal media has wasted two years trying to manufacture a fake collusion scandal instead of reporting the fact that unlike president Obama, who let Russia and other foreign adversaries push America around, President Trump has actually been tough on Russia," Sarah Huckabee Sanders, the White House press secretary, said in a statement. Trump has been in contact with Putin since shortly after his election in November 2016. Putin sent him a congratulatory telegram and the two spoke by telephone on November 14. They spoke a few more times before meeting in person for the first time as presidents on July 7, 2017, in Hamburg, Germany, during a Group of 20 economic summit. Aside from interpreters, the only others in the room were Rex W. Tillerson, then the secretary of state, and Sergey V. Lavrov, the Russian foreign minister. Vladimir Putin and Donald Trump meeting in Hamburg, Germany, on July 7, 2017. Credit:AP The inaugural meeting came at a sensitive time. Trump's team learned that day that one of the biggest secrets of his presidential bid was about to become public: At the height of the campaign, his son, son-in-law and campaign chairman had met at Trump Tower with Russians on the promise of obtaining dirt on Hillary Clinton from the Russian government. Trump's team was scrambling to respond to a request for comment by the Times.

Trump's meeting with Putin that day lasted more than two hours. Afterward, Trump took his interpreter's notes and instructed the interpreter not to brief anyone. Tillerson told reporters that the leaders discussed everything from Syria to Ukraine, but he also described "a very robust and lengthy exchange" on the election hacking. A few hours later, Trump sought out Putin again during a dinner for all the leaders. Videotape later made public showed Trump pointing at Putin, who was seated across and down a long table, then pointing at himself and then making a pumping motion with his fist. Trump later told the Times that he went over to see his wife, Melania Trump, who was sitting next to Putin, and the two leaders then talked, with Putin's interpreter translating. No US officials were present, and the White House did not confirm the encounter until more than 10 days later, after it was independently reported. The day after the two meetings, as Trump was on Air Force One taking off from Germany heading back to Washington, he telephoned a Times reporter and argued that the Russians were falsely accused of election interference. While he insisted most of the conversation be off the record, he later repeated a few things in public in little-noticed asides. He said that he raised the election hacking three times and that Putin denied involvement. But he said Putin also told him that "if we did, we wouldn't have gotten caught, because we're professionals." Trump said: "I thought that was a good point because they are some of the best in the world" at hacking.

Asked how he weighed Putin's denials against the evidence that had been presented to him by Comey; John O. Brennan, then the CIA director; and James R. Clapper jnr, then director of national intelligence, he said that Clapper and Brennan were the "most political" intelligence chiefs he knew and that Comey was "a leaker." Later on the same flight to Washington, Trump huddled with aides to decide how to respond to the emerging story by other Times reporters about the Trump Tower meeting. He personally dictated a misleading statement, saying the meeting was about Russian adoptions without admitting that it was actually intended to accept Moscow's aid for his campaign, as emails obtained by the Times later documented. The confluence of the two conversations with Putin even as Trump's team was grappling with questions about the Trump Tower meeting have fuelled further suspicions. "If you add up all these pieces, it's a very damning picture at a minimum of how to handle national security," said Weiss, who is now at the Carnegie Endowment for International Peace. "If there's a more nefarious explanation, it's obviously more disturbing." Trump next encountered Putin in person on November 11, 2017, at a meeting of the Asia-Pacific Economic Cooperation forum in Da Nang, Vietnam. No formal meeting was scheduled, but the two chatted anyway, and Trump later indicated that Putin again denied any election interference. "I really believe that when he tells me that, he means it," Trump said.