President Trump on Sunday sought to move past allegations of Russian interference in the 2016 U.S. election, effectively dismissing the importance of the intelligence community’s definitive conclusion about a foreign adversary in pursuit of a collaborative partnership with Russian President Vladi­mir Putin.

Issuing his first public comments since sitting down with Putin in Germany, Trump vowed to “move forward in working constructively with Russia” and said the two leaders were discussing a cybersecurity unit that would protect against the kinds of illegal intrusions that U.S. intelligence agencies say Putin ordered in the United States.

After Putin denied in his meeting with Trump any such election interference, the U.S. president tried to turn the page altogether on the issue of Russian hacking. As special counsel Robert S. Mueller III investigates Russian interference and possible collusion with Trump campaign officials, Trump has repeatedly labeled the issue a hoax and has portrayed it as a dark cloud unfairly hanging over his first six months as president.

Trump’s pledge to partner with Putin drew swift and stern denunciations from both Democratic and Republican officials, who cast the U.S. president as dangerously naive for trusting his Russian counterpart and said Russia must be forced to pay a price for its election interference.

The president responded to the criticism late Sunday, tweeting his own doubts that a cyber unit could work. “The fact that President Putin and I discussed a Cyber Security unit doesn’t mean I think it can happen. It can’t — but a ceasefire can, & did!” he wrote, referring to an agreement among the United States, Russia and Jordan in a region of Syria.

(Victoria Walker/The Washington Post)

Trump said that he “strongly pressed” Putin twice about Russian meddling and that Putin “vehemently denied it.” Trump did not indicate whether he accepted Putin’s denial, saying only, “I’ve already given my opinion.”

[Putin denies election hacking after Trump pressed him, Tillerson says]

Trump delivered his account of the meeting with Putin, held Friday on the sidelines of the Group of 20 summit in Hamburg, via several defiant tweets fired off Sunday morning from the White House, just before he visited his Northern Virginia golf course — as opposed to in a news conference such as the one Putin held with journalists on Saturday.

Putin and Russian Foreign Minister Sergei Lavrov said Trump believed Putin’s assurances that Russia did not interfere in the election.

“It seemed to me that he took it into account and agreed,” Putin told reporters Saturday, although he added, “You should ask him.”

Initially, U.S. officials traveling with Trump would not dispute Putin’s and Lavrov’s accounts when asked by reporters. On Sunday, however, White House Chief of Staff Reince Priebus, who remained in Washington during the trip, rejected the Russian characterization.

“It’s not true,” Priebus said on “Fox News Sunday.” “The president absolutely did not believe the denial of President Putin.”

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U.S. intelligence agencies have concluded definitively that Russian authorities tried to influence the election in Trump’s favor with illegal hacking and propaganda and other activities.

Trump’s public comments on the issue have been far less definitive, varying widely from tepid acknowledgment to outright doubt about Russia’s role. Under questioning from “Fox News” host Chris Wallace, Priebus also showed varying degrees of certainty about whether Trump believes that Russia meddled in the election.

“He said they probably meddled in the election. They did meddle in the election,” Priebus said, seeming to grow more definitive. But then Priebus seemed to back off: “Yes, he believes that Russia probably committed all of these acts that we’ve been told of. But he also believes that other countries also participated in this activity.”

Trump on Sunday revealed his continued fixation with some aspects of the Russia issue. He falsely accused Barack Obama on Twitter of doing “NOTHING” after learning of the Russian hacking before the election. In fact, on Oct. 7, about a month before the election, the Obama administration formally and publicly blamed Russia for the hacking. Some Obama administration officials have since said that they regret not responding more forcefully.

[Obama’s secret struggle to punish Russia for Putin’s election assault]

Trump also chided the news media and, in the context of his meeting with Putin, claimed vaguely that “questions were asked” about the level of cooperation between intelligence agencies and the Democratic National Committee, whose email server was among those allegedly compromised by the Russians.

John Brennan, who served as CIA director under Obama and ran the agency’s response to Russia’s election interference, chastised Trump on Sunday for repeatedly casting doubt on the conclusions of the intelligence community, including at a news conference last week in Poland.

“I seriously question whether or not Mr. Putin heard from Mr. Trump what he needed to about the assault on our democratic institutions,” Brennan said on NBC’s “Meet the Press.”

Brennan added of Trump: “He said it’s an ‘honor’ to meet President Putin. An honor to meet the individual who carried out the assault against our election? To me, it was a dishonorable thing to say.”

Sens. John McCain (Ariz.), Lindsey O. Graham (S.C.) and Marco Rubio (Fla.) — three leading Republican hawks on Russia — said Sunday that Trump’s eagerness to partner with Putin was dangerous for the United States.

“When it comes to Russia, he’s got a blind spot,” Graham said on “Meet the Press.” “To forgive and forget when it comes to Putin regarding cyberattacks is to empower Putin, and that’s exactly what he’s doing.”

Rubio tweeted that Putin “will never be a trusted ally or a reliable constructive partner,” and that working with him to address cybersecurity threats was akin to partnering with Syrian President Bashar al-Assad to protect against chemical weapons.

McCain, meanwhile, lamented that Russia has faced “no penalty whatsoever” from the Trump administration for its hacking.

“We know that Russia tried to change the outcome of our election last November, and they did not succeed, but there was really sophisticated attempts to do so,” McCain said on CBS’s “Face the Nation.” “So far, they have not paid a single price for that.”

Invoking the language of Trump’s tweet, McCain added, “Yes, it’s time to move forward, but there has to be a price to pay.”

McCain championed a bill, passed overwhelmingly in the Senate last month, to slap additional sanctions on Russia. The Trump administration has said it opposes the measure because it preempts the president’s powers to apply sanctions.

During a visit to Ukraine, Secretary of State Rex Tillerson said Sunday that existing sanctions would remain in place until Moscow reverses its intervention in Ukraine and respects the border between the two countries.

Trump tweeted Sunday, “Nothing will be done until the Ukrainian & Syrian problems are solved,” adding a reference to Russia’s role in Syria’s civil war.

Trump also said the issue of sanctions was not discussed in his meeting Friday with Putin, contradicting what Tillerson, who was in attendance, told reporters soon after the meeting. Tillerson said that Trump “took note” of congressional efforts to push for additional sanctions against Russia but that he and Putin focused their discussion on “how do we move forward from here.”

[Tillerson vows relations with Russia will be frosty until it leaves Ukraine alone]

McCain said Tillerson was a weak advocate for American values abroad. Asked by CBS’s John Dickerson whether he regrets his Senate vote to confirm Tillerson as secretary of state, McCain said, “Sometimes I do.”

Trump said Sunday he was eager to work with Putin on what he described as an “impenetrable Cyber Security unit” the two men discussed forming “so that election hacking, & many other negative things, will be guarded.”

Tillerson explained the unit as a “framework under which we might begin to have agreement on how to deal with these very complex issues of cyberthreats, cybersecurity, cyberintrusions.”

Nikki Haley, the U.S. ambassador to the United Nations, defended her boss’s cooperation with Putin, saying “we won’t ever trust Russia” but that working with Russia on cybersecurity will “keep them in check.”

“From a cyber standpoint, we need to get together with Russia. We need to tell them what we think should happen, shouldn’t happen, and if we talk to them about it, hopefully, we can cut this out and get them to stop,” Haley said Sunday on CNN’s “State of the Union.”

She continued: “It doesn’t mean we’ve ever taken our eyes off of the ball. It doesn’t mean we ever trust Russia. We can’t trust Russia, and we won’t ever trust Russia. But you keep those that you don’t trust closer, so that you can always keep an eye on them and keep them in check, and I think that’s what we’re trying to do with Russia right now.”

Trump’s pledge to work with Putin on cybersecurity came as U.S. government officials told The Washington Post that Russian government hackers were behind recent intrusions into the systems of U.S. nuclear power and other energy companies.

The idea of a cyber partnership was roundly mocked. Former defense secretary Ashton B. Carter, who served under Obama at the time of Russia’s interference, likened it in a CNN interview to “the guy who robbed your house proposing a working group on burglary.”

McCain said facetiously on NBC, “I am sure that Vladimir Putin could be of enormous assistance in that effort, since he’s doing the hacking.”

Carol Morello in Kiev, Ukraine, and David A. Fahrenthold and David Weigel in Washington contributed to this report.