If the political interference documented in special counsel Robert Mueller's report was just the "tip of the iceberg," what else is lurking out of sight beneath the surface?

That was the question posed by Deputy Attorney General Rod Rosenstein in a speech in New York City, one in which he defended his handling of the Russia investigation and suggested there could be much more to it beyond that contained in Mueller's report.

"The bottom line is, there was overwhelming evidence that Russian operatives hacked American computers and defrauded American citizens, and that is only the tip of the iceberg of a comprehensive Russian strategy to influence elections, promote social discord and undermine America, just like they do in many other countries," Rosenstein said on Thursday.

Mueller's focus was on the two best-known aspects of Russia's "active measures": the theft and release of material embarrassing to political targets and the use of social media platforms to crank up agitation among an already divided populace.

Some of the Russian schemes that Mueller left out of his report also are known.

On Friday, for example, a federal judge sentenced a woman to 18 months in prison after she pleaded guilty to serving as an unregistered Russian agent from around 2015 until her arrest last summer.

Maria Butina's case was administratively separate from Mueller's investigation within the Justice Department, but prosecutors detailed what they called her clear efforts to try to burrow into the conservative political establishment, including through the National Rifle Association, as part of deliberate reconnaissance by the Russian regime of American politics.

Butina's American boyfriend, Paul Erickson, played a central role in her activities. He's facing criminal charges of his own related to alleged investment fraud, and it isn't clear yet whether prosecutors also may seek an indictment in connection with the activities described in court documents as part of Butina's mission within the United States.

Erickson has pleaded not guilty in his fraud case, and his attorney says he has done nothing wrong.

How much more could there be to Russia's interference operations? How much do American officials know about that they don't want to reveal? And how much might the Russians continue trying to do that the United States isn't following?

Attorney General William Barr could get questions along these lines this week when he appears before the Senate and then the House judiciary committees. And Mueller himself almost certainly will if he appears before Congress.

The ongoing threat

Russia is a "very significant counterintelligence threat," as FBI Director Christopher Wray said Friday.

He told an audience at the Council on Foreign Relations that the interference campaign that peaked in 2016 has never really ended and continued through last year's election — and he expects it to run through the 2020 race.

"That is not just an election-cycle threat; it's pretty much a 365-days-a-year threat," Wray said. "And that has absolutely continued."

American officials aren't sitting on their hands, the FBI director said, but the amount of chaos that Russia has been able to cause with what it calls "Project Lakhta" at relatively low cost means that the government is going to need to work to keep up.

"On the one hand, I think enormous strides have been made since 2016 by all the different federal agencies, state and local election officials, the social media companies, et cetera," Wray said. "But I think we recognize that our adversaries are going to keep adapting and upping their game. And so we're very much viewing 2018 as just kind of a dress rehearsal for the big show in 2020."

For all their broad warnings, however, national security officials often leave out the details.

In fact, Rosenstein said the focus of the Russia investigation within the Justice Department — which has the ultimate job of assessing whether laws were broken, as compared with a special panel such as the 9/11 Commission — always meant that not every question about the Russia imbroglio would be answered.

"I did pledge to do it right and take it to the appropriate conclusion," he said. "I did not promise to report all results to the public, because grand jury investigations are ex parte proceedings" — meaning they take place outside of public view.

Continued Rosenstein: "It is not our job to render conclusive factual findings. We just decide whether it is appropriate to file criminal charges."

Hints, clues, leads

There have been suggestions beyond the Butina case about other aspects of Russia's "active measures" campaign.

One unresolved question was whether Moscow might have been responsible for creating fraudulent documents that further complicated the FBI's investigation into Democratic nominee Hillary Clinton's email server in 2016, as The Washington Post reported.

Another possibility that has come up before is that Russia's military intelligence agency, the GRU, could be holding emails or other data from Republicans stolen before the better-known campaign that targeted Democrats.

One theory aired in the past — including, at one point, by President Trump — is that the Russian government might intervene to support Democrats in future elections, interested more in simply creating chaos than in sustaining Trump's presidency.

Another question mark in terms of public awareness is the extent to which Russian cyberattacks have compromised state elections systems, including those used by government officials or their vendors.

Wray and other officials maintain that no vote has ever been changed by a remote technical compromise. That doesn't mean the GRU or its siblings have stopped trying — and the prospect that a voter's choice might not be counted correctly continues to be one of Americans' leading concerns about the threat of foreign interference.

Analysts also have warned that foreign interference specialists could be refining the techniques they use to fool Americans into believing false claims, including with sophisticated new fake video or audio.

If a clip appeared at a critical moment in a campaign in which a political figure were depicted saying something controversial — and no one knew immediately whether it was real — that could have big potential consequences at a critical moment in an election.

Whichever types of schemes are selected by foreign nations — Russia or otherwise — anticipating political mischief must be the new normal. Wray was asked whether the results of 2016 meant that China, North Korea, Iran or others might join in, too.

"Certainly, all those countries are watching and taking note of what the Russians attempted to do in 2016 and since," he said. "And I think we expect that this is going to become a phenomenon we're going to have to contend with, with a lot more than just Russia."

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