WASHINGTON — The Mueller report's narrative of secret meetings between members of Donald Trump's orbit and Russian operatives — contacts that occurred both before and after the 2016 election — portrays a political campaign that left itself open to a covert Russian influence operation, former intelligence officials and other experts say.

While finding no criminal conspiracy, the report shows that Trump associates met with Russians after the intelligence community said in October 2016 that Russia was interfering in the presidential election, and even after the Obama administration announced a set of post-election sanctions to punish Russia for that behavior.

The 448-page report, written as a prosecutorial document, was not meant to assess, and does not say, whether U.S. national security was put at risk through those contacts. But former FBI and CIA officials and people who study Russian intelligence say the report describes a counterintelligence minefield — senior members of a presidential campaign and transition holding secret talks with a sophisticated foreign adversary, without the benefit of State Department and intelligence community counsel.

"The Russians came up against a group of people who were not intelligence savvy and who were predisposed not to listen to the intelligence and counterintelligence community," said Luis Rueda, who spent 27 years as a CIA operations officer. "The Russians made a very bold and aggressive attempt to take advantage of that — to try to compromise people, to try to leverage their access."

The FBI, as part of its counterintelligence mission, is continuing to investigate Russian attempts to influence the Trump administration and assess the national security damage from Russia's 2016 effort, current and former U.S. officials tell NBC News.

Democratic lawmakers have demanded a briefing on the counterintelligence findings of the Russia investigation and the status of the FBI's counterintelligence investigation into Trump.

John Sipher, who served in Moscow and once helped run CIA spying operations against Russia, said, "It's clear that the Russians had a pretty extensive full court press on this administration." The full extent of how successful it was may never be known, he said.

"Being able to lock it down and prove in court? That only comes when you catch somebody red-handed, or when you have a source on the inside of your adversary who hands you documents."

The Mueller report says the special counsel investigated whether Russia's wooing of Trump officials "constituted a third avenue of attempted Russian interference with or influence on the 2016 presidential election," in addition to Russian hacking of Democratic emails and social media manipulation through false personas.

Without explicitly answering that question, the Mueller report explains how Russia sought to secretly influence the incoming Trump administration after helping it get elected, and how Kushner and other senior members of the Trump team embraced those entreaties. The report describes meetings with questionable individuals and a ready use of backchannel communications, despite warnings from U.S. intelligence officials.

"The investigation established multiple links between Trump Campaign officials and individuals tied to the Russian government," the report says. "Those links included Russian offers of assistance to the Campaign. In some instances, the Campaign was receptive to the offer, while in other instances the Campaign officials shied away."

After the election, the report says, "Russian government officials and prominent Russian businessmen began trying to make inroads into the new administration. The most senior levels of the Russian government encouraged these efforts."

Republican presidential candidate Donald Trump speaks during a campaign rally at the University of Wisconsin Eau Claire, Tuesday, Nov. 1, 2016, in Eau Claire, Wis. Evan Vucci / AP

Trump officials took those meetings knowing their campaign had benefited from information stolen by the Russian government, the Mueller report says. NBC News reported that the Trump campaign received a counterintelligence briefing in the summer of 2016 warning that it could be the subject of Russian spying and infiltration attempts.

The fact that the Trump team did not coordinate their Russia meetings with the U.S. government gave the Russians leverage, Sipher and other experts say. U.S. government officials with security clearances who fail to report contacts with Russian nationals could lose their security clearances or their jobs.

Mueller's report did not address how unusual and potentially dangerous it might be for representatives of an incoming American administration to meet secretly with a foreign adversary, without benefit of advice from career CIA and State Department officials.

But in a separate court case this week, the Justice Department submitted an affidavit from a former head of counterintelligence for the FBI, who explained his view of the dangers of so-called backchannels. It came in the case of Maria Butina, the Russian former college student who has pleaded guilty to acting as an unregistered agent of Russia. Prosecutors are recommending an 18-month prison sentence.

Butina, who is not mentioned in the redacted Mueller report, was seeking to expand Russian influence on Republicans and the National Rifle Association at the direction of a senior Russian central banker, court records show. She did so by cultivating influential Americans who did not know she was working on behalf of the Russian government, the documents say. Her goal, the documents say, was to open unofficial channels of communication between the Russian government and key Americans.

"Butina's stated goal of establishing a backchannel of communication, if it had been achieved, would have benefited the Russian government by enabling Russia to bypass formal channels of diplomacy, win concessions, and exert influence within the United States," wrote Robert Anderson, a former head of counterintelligence for the FBI, in the affidavit. "Such benefits to the Russian government would have carried with them commensurate harm to the United States, including harm to the integrity of the United States' political processes and internal government dealings, as well as to U.S. foreign policy interests and national security."

Political influence — in addition to recruiting spies and stealing defense secrets — is a main goal of intelligence operations against the U.S. by Russia, Anderson said.

The U.S. "is Russia's primary target for malign and intrusive intelligence operations," Anderson said. "Russia works to obtain not only classified material or trade secrets, but also to collect any information that could, by itself or in conjunction with other efforts, assist the Russian government in increasing its geopolitical power or undermining and harming that of the United States."

"In my expert opinion, Butina provided the Russian Federation with information that skilled intelligence officers can exploit for years and that may cause significant damage to the United States."

Maria Butina, leader of a pro-gun organization in Russia, speaks to a crowd during a rally in support of legalizing the possession of handguns in Moscow, Russia. AP file

Andrew Weiss, a Russia expert at the Carnegie Endowment for International Peace, cited Anderson's affidavit this week as evidence that the Mueller report's narrative of Trump-Russia contacts is damning.

"Seen against this backdrop, it's clear that the conduct outlined in Volume I of the Mueller Report created enormous damage to US national security," Weiss tweeted. "Anderson is scathing about the impact of back channel amateur hour."

In an interview, Weiss said that while the Trump administration has not given Russia the total reset in relations it was hoping for, Trump has consistently followed Putin's lead on a number of matters, such as a plan to create a joint U.S.-Russia cybersecurity agency, or Trump's agreement that he would help Putin repatriate Syrian refugees displaced by civil war. Both ideas were quickly walked back by senior U.S. officials.

Trump has repeatedly praised Russian President Vladimir Putin, resisted acknowledging Russian election interference, and denigrated the NATO alliance.

President Donald Trump and Russian President Vladimir Putin, right, pose for a photograph at the Presidential Palace in Helsinki, Finland, on July 16, 2018. Alexei Nikolsky / AP file

In July, after a Trump-Putin summit in Helsinki, Trump seemed to accept Putin's denial that Russia had interfered in the 2016 election, dismissing the findings of American intelligence agencies.

"My people came to me. Dan Coats came to me, and some others," Trump said, referring to the director of national intelligence. "They said they think it's Russia," Trump said. "I have President Putin. He just said it's not Russia. I will say this: I don't see any reason why it would be."

Russian outreach after the election

Many of the interactions between the Trump campaign and Russians outlined in the Mueller report had been previously detailed in news reports, including conversations between Michael Flynn, Jared Kushner and the Russian ambassador — and Kushner's request to use a secure communications channel in the Russian embassy. But the report offered new insights into Russian outreach after the election.

According to the report, in December 2016 Putin told Petr Aven, head of Russia's largest commercial bank, Alfa-Bank, that he was concerned about the U.S. imposing sanctions. Putin complained that he wasn't sure who to speak to in the incoming Trump administration, Aven told Mueller's office.

"Aven told Putin he would take steps to protect himself and the Alfa-Bank shareholders from potential sanctions, and one of those steps would be to try to reach out to the incoming Administration to establish a line of communication," the report says.

Aven enlisted Richard Burt, the former U.S. ambassador to Germany and an Alfa-Bank consultant, to help contact members of the Trump transition team. The report says Burt approached Dimitri Simes, head of a Russian-aligned think tank in Washington, the Center for the National Interest.

At the time, Simes was lobbying the Trump transition team, on Burt's behalf, to appoint Burt U.S. ambassador to Russia, the report says. Simes told Burt that a secret channel wasn't a good idea, given the media attention to Trump's dealings with Russia.

But another senior Russian official, Kirill Dmitriev, the head of Russia's sovereign wealth fund and a close Putin associate, did succeed in establishing a secret channel to the Trump team, the report says.

"We want to start rebuilding the relationship in whatever is a comfortable pace for them," Dmitriev wrote in a message to George Nader, an international consultant who helped broker the outreach.

Dmitriev ended up meeting with Erik Prince, a Trump supporter and associate of Steve Bannon, at a resort in the Seychelles.

Rick and Libi Gerson attend a film benefit in New York in 2012. D Dipasupil / FilmMagic

The meeting was a disappointment to Dmitriev, the Mueller report says, because "he believed the Russians needed to be communicating with someone who had more authority within the incoming Administration than Prince had." And "he had hoped to have a discussion of greater substance, such as outlining a strategic roadmap for both countries to follow."

Soon enough, Dmitriev found another route, He reached out to a friend of Kushner, Rick Gerson, a hedge fund manager. The two talked about potential joint ventures between the Russian wealth fund and Gerson's fund, the Mueller report says. And together they worked on a proposal for reconciliation between the United States and Russia, which Dmitriev implied he cleared through Putin, the report says.

"On January 16, 2017, Dmitriev consolidated the ideas for U.S.-Russia reconciliation that he and Gerson had been discussing into a two-page document that listed five main points: (1) jointly fighting terrorism; (2) jointly engaging in anti-weapons of mass destruction efforts; (3) developing "win-win" economic and investment initiatives; (4) maintaining an honest, open, and continual dialogue regarding issues of disagreement; and (5) ensuring proper communication and trust by 'key people' from each country."

Gerson sent the two-page proposal to Kushner before the inauguration, and Kushner later gave copies to Bannon and then-Secretary of State Rex Tillerson, the report says.

Gerson and Dmitriev appeared to stop communicating with each other in March 2017, the report says, "when the investment deal they had been working on together showed no signs of progressing."

"It's classic foreign intelligence activity on the part of the Russians," said David Gomez, a former FBI agent whose specialties included counterintelligence. "The Russians are trying to develop unwitting assets. If they can entice Eric Prince, if they can entice Jared Kushner, if they can entice Donald Trump into secretly dealing with them, they have essentially opened a back door into the administration and the U.S. government."

Tough on Russia

Pushing back on criticism about the administration's Russia stance, White House officials say they have been much harder on Russia than President Barack Obama was.

"There's never been a president as tough on Russia as I have been," Trump told reporters last year, echoing comments he has made many times.

The chief executive of the Russian Direct Investment Fund, Kirill Dmitriev, waits before a meeting of Russian President Vladimir Putin with representatives of the foreign business community on the sidelines of the Eastern Economic Forum in Vladivostok, Russia on Sept. 11, 2018 Valery Sharifulin / Tass / Pool via Reuters file

The Trump administration has imposed additional sanctions on Russia and provided lethal assistance to a Ukrainian government that is battling a Russian incursion.

Still, Trump's unwillingness to call out Russian election interference makes it easier for Russia to succeed in 2020, former senior intelligence officials tell NBC News. Just this week, son-in-law Kushner dismissed Russian interference as "a few Facebook ads" and said the Mueller probe was more damaging to the U.S. than anything Russia did. Russia's English-language propaganda network, RT, was quick to embrace Kushner's stance.

"The Trump White House is like a juicy peach waiting for the Russians to come and pluck it," one former official said, "and Trump is not moving the branches away from them."