Washington (CNN) President Donald Trump appeared to back away Sunday night from an earlier tweet about "forming an impenetrable Cyber Security unit" with Russian President Vladimir Putin.

Sunday morning, Trump, who met for over two hours Friday with Putin on the sidelines of the G20 summit in Hamburg, Germany, unexpectedly raised the possibility of such a unit.

"Putin & I discussed forming an impenetrable Cyber Security unit so that election hacking, & many other negative things, will be guarded ... and safe," Trump wrote.

Putin & I discussed forming an impenetrable Cyber Security unit so that election hacking, & many other negative things, will be guarded..

The suggestion immediately raised eyebrows and suspicions from both American and allied intelligence officials and lawmakers. US intelligence agencies have concluded that Russia, at Putin's behest , was behind efforts to meddle in the 2016 presidential election, findings that Trump tepidly endorsed at a news conference in Warsaw, Poland, on Thursday.

Sunday night, Trump downplayed his suggestion of a joint US-Russia cybersecurity effort.

"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!" Trump tweeted, referring to an agreement the two nations reached over Syria.

US and Russian officials have disputed accounts of the discussion between Trump and Putin over the election meddling, which was discussed at their Friday meeting. Trump, hours after returning from his second foreign trip as president, declined to refute the Russian account of his meeting with Putin, leaving their assertion that he accepted the Russian president's denial of 2016 election meddling unchallenged.

Minutes after Trump's meeting with Putin, Russian Foreign Minister Sergey Lavrov went on camera and told reporters that Trump accepted Putin's assurances there was no Russian involvement in the 2016 American election.

"President Trump said he's heard Putin's very clear statements that this is not true and that the Russian government didn't interfere in the elections and that he accepts these statements. That's all," Lavrov said, according to a CNN translation.

A senior Trump administration official immediately denied that Trump accepted Putin's claim of non-interference. But no top Trump aides immediately said -- on the record -- that Trump didn't accept Putin's explanation. Asked three times about how Trump responded to Putin on Saturday, chief economist Gary Cohn, national security adviser H.R. McMaster, and Treasury Secretary Steven Mnuchin all declined to knock down those remarks when pressed by reporters, deferring instead to Trump himself.

"President Trump will be happy to make statements himself about that," Mnuchin said. "But President Trump handled himself brilliantly. It was very clear that he made his position felt, and after a very substantive dialogue on this, they agreed to move on to other discussions."

Trump, according to Secretary of State Rex Tillerson, pressed Putin on election meddling and then moved on.

US Ambassador to the United Nations Nikki Haley said Putin denied Moscow interfered in last year's US election in order to "save face."

"This is Russia trying to save face, and they can't, they can't," Haley told CNN's Dana Bash on "State of the Union" Sunday. "Everybody knows that Russia meddled in our elections. Everybody knows that they're not just meddling in the United States' election. They're doing this across multiple continents, and they're doing this in a way that they're trying to cause chaos within the countries."

Later, speaking on "Fox News Sunday," White House chief of staff Reince Priebus disputed Lavrov's remarks, saying Trump "absolutely did not believe the denial of President Putin."

On Twitter Sunday morning, Trump wrote, "I strongly pressed President Putin twice about Russian meddling in our election. He vehemently denied it. I've already given my opinion."

He was apparently referring to his comments in Warsaw, when he said, "I think it was Russia but I think it was probably other people and or countries. I see nothing wrong with that statement."

He added: "Nobody really knows. Nobody really knows for sure."

CORRECTION: This story has been updated to reflect that Priebus disputed Lavrov's comments about the Trump-Putin exchange on the subject of Russian interference in the US election.