President Trump said Saturday that Russian President Vladimir Putin again denied that Moscow tampered in the U.S. presidential campaign last year.

The two men had brief conversations during a larger meeting of the Asia-Pacific Economic Cooperation forum in Danang, Vietnam, before Trump flew to Hanoi for a bilateral meeting Sunday with Vietnamese leaders.

Trump said that he had "two or three" brief conversations with Putin mostly centered on the war in Syria, but added that he pressed the Russian leader on Moscow's role in attempting to interfere in the 2016 election.

"He said he didn't meddle," Trump said, answering questions in the press cabin on Air Force One. "I asked him again. You can only ask so many times. . . . He said he absolutely did not meddle in our election. He did not do what they are saying he did."

Trump said that he believed Putin was "sincere" in his denials, and that Putin seemed to find the question insulting. Suggesting that what he called the "artificial Democratic hit job" of investigations of his campaign were preventing U.S.-Russian cooperation on a range of issues, including North Korea, Trump said that it is "a shame, because people will die because of it."

In his own news conference after their talks, Putin said he knew "absolutely nothing" about contacts with Trump campaign officials, and called reports that a campaign official sought a meeting with his niece "bollocks," according to an interpreter.

"They can do what they want, looking for some sensation," Putin said of the investigations. "But there are no sensations."

Putin said he and Trump "hardly know each other," but described the U.S. president as "very professional, very friendly, he behaves very appropriately. Unfortunately, we did not have enough time to get down to some more details," he said, "because we have many matters to discuss."

He blamed the lack of a formal meeting between the two at the conference on the "failure" of their respective teams, and said they would be "lectured" on the lapse.

The two leaders issued a joint statement pledging to continue their cooperation to defeat the Islamic State in Syria, and their commitment to U.N.-brokered peace negotiations between the government of Syrian President Bashar al-Assad and opponents fighting to oust him.

Trump also described former FBI director James B. Comey, who testified to Congress that Trump asked him to drop an investigation of his campaign's ties to Russian officials, as a proven "liar" and "leaker." Trump called the former U.S. intelligence officials who concluded that the Russians tampered — including former director of national intelligence James R. Clapper Jr. and former CIA director John Brennan — "political hacks."

Clapper, Brennan and Comey, on behalf of the 17-agency intelligence community, issued a report in January describing an unprecedented Russian intelligence operation to undermine public faith in the U.S. democratic process and help elect Trump.

The intelligence agencies have said that Russian hackers stole and made public thousands of emails from the Democratic National Committee, also spread misinformation in an attempt to help Trump beat Democrat Hillary Clinton. Trump, however, has said he does not believe that Russia actively sought to help him.

The assessment sparked ongoing, separate investigations by Congress and special counsel Robert S. Mueller III, a former FBI director, of Russian interference in the campaign. Those inquiries include determining whether there was any collusion between the Russians and the Trump campaign.

Trump said that Putin "is very, very strong in the fact that he didn't do it. You have President Putin very strongly, vehemently, says he has nothing to do with that. Now, you are not going to get into an argument, you are going to start talking about Syria and the Ukraine."

Sen. Mark R. Warner (Va.), the ranking Democrat on the Senate Intelligence Committee, said in a statement that he was left "completely speechless" by Trump's willingness "to take the word of Vladi­mir Putin, a former intelligence operator who spent years working against us, over the conclusions of our own combined intelligence community."

In response to questions about Trump's remarks, the CIA issued a statement saying that Director Mike Pompeo "stands by and has always stood by the January 2017 Intelligence Community assessment. . . . The intelligence assessment with regard to Russian election meddling has not changed." The assessment did not address whether Russian meddling altered the election outcome.

[New York Times photographer tweets ‘photo’ of black box to protest White House coverage blackout]

Mueller's team recently brought indictments against former Trump campaign chairman Paul Manafort and an associate, Richard Gates, alleging that between 2006 and 2016, they attempted to launder money made as consultants to Russian-allied leaders in Ukraine and that they had acted as unregistered agents for a foreign government.

"There was no collusion," Trump said on the plane. "Everybody knows there was no collusion."

He labeled "phony" a dossier compiled by a former British intelligence agent alleging ties between Trump and Moscow. The document was later turned over to U.S. law enforcement authorities. Many of the allegations have not been independently confirmed.

Trump also cast blame on former president Barack Obama and Clinton, a former secretary of state, who famously attempted a "reset" of U.S. relations with Russia during Obama's first term. Trump referred to Clinton's "stupid reset button," in which she presented Russian Foreign Minister Sergei Lavrov with an oversize "reset button" that erroneously used the Russian word for "overload" instead of "reset."

"Hillary tried it, she failed, nobody mentions it," Trump said. "She hit that reset button. It was a joke. But she tried and she failed." Trump said that Obama had bad chemistry with Putin and that Clinton was "in way over her head."

When Trump was asked during the flight to Hanoi whether he believed Putin's denial of tampering, he said: "Every time he sees me, he says, 'I didn't do that,' but I really believe that when he tells me that, he means it. . . . I think he's very insulted by it, and that's not a good thing for our country."

Trump met with Putin this summer on the sidelines of the Group of 20 summit in Germany, after which he said Putin issued similar denials. Both then and now, Trump did not directly respond to questions as to whether he believes Putin.

[Trump had undisclosed hour-long meeting with Putin at G-20 summit]

On a different topic, Trump was asked whether Roy Moore, the Republican nominee in the U.S. Senate race in Alabama, should drop out of the race over allegations that he had sexual contact with a 14-year-old girl when he was 32 . White House press secretary Sarah Huckabee Sanders told reporters two days ago that Trump thinks that "mere allegations" are not enough to "ruin" Moore's life but that if the allegations are true, he should "do the right thing and step aside."

Trump said he has been too busy during the Asia trip to focus on the allegations against Moore.

"Believe it or not, even when I'm in Washington or New York, I do not watch much television," he said. "I know they like to say that. People that don't know me, they like to say I watch television — people with fake sources. You know, fake reporters, fake sources. But I don't get to watch much television. Primarily because of documents. I'm reading documents. A lot. And different things. I actually read much more. I read [articles by] you people much more than I watch television. But anyway. So I have not seen very much about him, about it. And you know I put out a statement yesterday that he'll do the right thing."

Nakamura reported from Danang, Vietnam. DeYoung reported from Washington.