President-elect Donald Trump's dismissal of U.S. intelligence findings that Russia tried to sway the presidential election is a distressing slap in the face to the intelligence community, current and former U.S. intelligence officials said Sunday.

Trump on Sunday repeated his rejection of the intelligence community's conclusion that Russia actively worked to help him win the election, calling the idea "ridiculous" in an interview on "Fox News Sunday."

The comment, like others that Trump made during the campaign, "is contrary to all that is sacred to national security professionals who work day and night to protect this country," a U.S. intelligence official told NBC News.

The official called it "concerning" that the president-elect has chosen to "impugn the integrity of U.S. intelligence officials" by disputing professional intelligence judgments as false or politically partisan.

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A congressional official with knowledge of the issue told NBC News on Saturday that the CIA has concluded that Russia mounted a covert intelligence operation to help Trump win the election.

Another source briefed on the intelligence told NBC News that the U.S. government has identified specific Russian actors it believes were involved in computer systems hacks — based on intercepted communications, human tips and computer forensics.

Trump dismissed such reports in a statement Friday that derided the CIA as "the same people that said Saddam Hussein had weapons of mass destruction."

A former senior intelligence official also noted Trump's assertion Sunday on Fox News that he doesn't always take the Presidential Daily Briefing — the top-secret briefing on national security developments — because "I'm, like, a smart person."

Related: Trump Once (Wrongly) Criticized Obama for Not Attending Intel Briefings

"It is curious that someone who refuses to take intelligence briefings has decided that he doesn't agree with the analysis contained in them," the former official said.

Rep. Adam Schiff of California, the top Democrat the House Intelligence Committee, also blasted Trump, saying the integrity of the electoral process is called into question "when President-elect Trump and his transition team minimize or dismiss the intelligence assessments themselves."

"Even more damaging are comments that impugn the tens of thousands of Americans who are at work every day of the year, many in great physical danger, to protect us and to provide our national leadership — regardless of political party — with the best information possible," Schiff said Saturday.

"Perhaps, once he has taken office, Mr. Trump will go to the CIA and look at the rows of memorial stars in the lobby — each representing a fallen officer — and reflect on his disparagement of the intelligence community's work," he said.