Russian spies seek a White House source “They want to know who is a mover and shaker in our society,” an expert said.

 -- It’s every Russian spy’s dream: to recruit a source inside the White House — or any place of power in Washington.

According to U.S. intelligence officials, there’s no dispute that the Russians are indeed making great efforts to get close to President Donald Trump and the people around him, whether those targeted know it or not.

“They always targeted political figures,” David Major, a retired FBI counterintelligence agent explained to ABC News. “They want to know who is a mover and shaker in our society, who affects it.”

And today as questions continue to mount over what contacts Trump campaign aides may have had with Russian intelligence operatives, the White House continues to dispute media reports that any of the president’s associates had such contact while on the campaign trail.

U.S. intelligence officials say the Russians are engaged in a massive campaign to infiltrate and disrupt American politics. It has gone on for decades, originally with the Cold War goal of placing a mole inside the White House, a retired KGB officer who once ran spy operations in Washington told ABC News.

A senior intelligence official told ABC News last night that no evidence gathered by the FBI so far suggests Trump associates knew they were talking to Russian intelligence officers. Those contacts being scrutinized by the FBI were first reported by The New York Times on Wednesday.

“These are not all sophisticated people, but they should have assumed or considered their Russian contacts might be spy service agents too,” the official briefed on the investigation said.

Russia has repeatedly denied making contact with Trump aides during the campaign. The Russian Embassy declined requests for an interview this week. But in media reports, Kremlin press secretary Dmitry Peskov has called the allegations "ridiculous."

The current version of Russia’s espionage and political influence program has likely included so-called cut-outs and front men — people and organizations that can extract prized intelligence, gain influence or create upheaval without the targeted Americans’ ever knowing who they’re really dealing with.

Sen. Mark Warner, D-Va., the top Democrat on the Senate Intelligence Committee, told ABC News, “This is a theory of war, a 21st century theory of war that includes false information, that includes cyberhacking, that includes, you know, in effect, sowing chaos.”

His committee is investigating Russian efforts to meddle in the recent election, and — as part of that bipartisan investigation — whether anyone in the Trump campaign was involved.

“I think this investigation is maybe the most serious thing that I’ll take on in my public career,” Warner said. “To me, what the Russians did in terms of their blatant interference in our election is unprecedented.”

The White House remains under fire over the ouster of National Security Adviser Michael Flynn, who was seen in a video in Moscow in December 2015 seated next to Russian President Vladimir Putin at a celebration for a Russian propaganda station. At the time, Flynn was about to become the senior foreign policy adviser for Trump and was paid to attend the event.

On Monday, Flynn was fired by Trump after media reports suggested the top security adviser had likely had inappropriate conversations with the Russian ambassador over U.S.-imposed sanctions on Russia before he was appointed to his official government role. Flynn almost certainly won't face criminal charges for anything, though he may not have been completely forthcoming in an FBI counterintelligence interview, two officials said.

The Defense Intelligence Agency, which Flynn led until former President Obama had him dismissed over management issues, suspended the retired Army lieutenant general's security clearance yesterday. The DIA held his top secret/sensitive compartmented information clearance, and it is not uncommon for a clearance to be suspended during an investigation.

Flynn did not respond to a message left for him on Wednesday.

Now the question for Senate investigators and the FBI is why the Russians may have been courting Flynn going back as far as 2015 after his retirement and how he reacted to that effort.

“If by his actions — implied or implicit — there was an effort to undermine American foreign policy, that bothers me a great deal,” Warner said.

But Flynn isn’t the only one who is being examined.

Carter Page, a former Trump campaign foreign policy adviser, is also under the investigator’s magnifying glass.

Page, claims he’s done major business deals in Russia and defends its leaders — moves that raise the eyebrows of American intelligence officials.

Asked by ABC News’ Brian Ross whether he agreed that Putin was a “thug,” Page said he “thoroughly” disagreed.

Page is named as a central figure in the now infamous dossier that makes unsubstantiated allegations that the Trump campaign and the Russians were in cahoots.

In an interview with ABC News in January, Page called allegations that he was meeting with Kremlin officials on behalf of the campaign to coordinate the release of damaging information on Trump’s opponents “so ridiculous that it’s completely false and laughable.”

And then there is Paul Manafort, a former Trump campaign manager, who once worked for pro-Russian politicians in Ukraine.

He too denies knowingly talking with anyone in Russian intelligence during the campaign, telling ABC News, “How am I supposed to know who is a Russian spy?”

The intrigue heightened late Wednesday when The Wall Street Journal picked up claims that U.S. intelligence officers were withholding intelligence from the 45th president over eroded trust because of his associates' Russian contacts and the FBI scrutiny of the White House.

But numerous officials said that was absurd.

“Any suggestion that the U.S. intelligence community is withholding information and is not providing the best possible intelligence to the president and his national security team is not true," the director of national intelligence’s public affairs office said in a statement.

ABC News’ Randy Kreider, Paul Blake, Alex Hosenball and Cho Park contributed to this story.