Special Counsel Robert Mueller and his prosecutors haven't concluded their investigation into whether President Donald Trump or any of his associates helped Russia interfere in the 2016 election, according to a person with knowledge of the probe.

Friday's indictment of a St. Petersburg-based” troll farm” and 13 Russian nationals should be seen as a limited slice of a comprehensive investigation, the person said. Mueller's work is expected to continue for months and also includes examining potential blockage of justice by Trump, said the person, who requested anonymity to discuss an investigation that is largely confidential.

A federal grand jury indicted the Russians for what it alleged was a vast scheme to interfere in the 2016 election and help Trump win. But Deputy Attorney General Rod Rosenstein said at a press conference Friday that there is” no accusation in this indictment that any American was a knowing participant” in the alleged scheme.

Read more: Mueller Accuses Russians of Pro-Trump, Anti-Clinton Meddling

Trump indicated that he believes the indictment exonerates him and his campaign.

” Russia started their anti-US campaign in 2014, long before I announced that I would run for President. The results of the election were not impacted. The Trump campaign did nothing incorrect – no collusion !” Trump said on Twitter .

That has yet to be determined. Friday's indictment should be seen as an effort by Mueller to raise awareness about Russia's capabilities as the 2018 U.S. elections draw near, the person or persons said.

It's still possible that Mueller will indict Americans for knowingly helping Russia, the person said.

By contrast, Trump and those around him portrayed the Russia investigation as if it were all but closed.” I am happy for the country. Bob and his team did a very good undertaking on this ,” Trump lawyer John Dowd said, although he declined to say if the action clears the president.

Shaky Ground

Rosenstein, who has been on shaky ground with Trump from the time he named Mueller as special counseling, offered a summary of the indictment that conspicuously skipped its repeated references to the Russian goal of helping Trump win the presidency and hurting his Democratic adversary Hillary Clinton.

Instead, Rosenstein singled out a post-election instance of efforts to create commotion, quoting accusations the Russians allegedly staged simultaneous rallies to support President-elect Trump and” to protest his election .”

Asked if Trump officers had been “duped” by the Russians, Rosenstein, said,” The defendants took extraordinary steps to make it appear that they were ordinary American political activists .”

Still, implicit in Rosenstein's words – and his appearance to announce the indictment – was an endorsement of the work of Mueller, who like Rosenstein has faced intense scrutiny. The indictments inspired a wave of statements from lawmakers in both parties backing the special attorney and demanding action against Russia.

Congressional Reaction

Representative Jerrold Nadler, a New York Democrat who's the ranking member on the House Judiciary Committee, said the proclamation Friday should “lay to rest” assertions the investigation was a hoax and preempt efforts to remove officials involved in investigating Trump.

” At this phase, any step President Trump may take to interfere with the Special Counsel's investigation — including removing Deputy Attorney General Rosenstein, or threatening to remove Special Counsel Mueller immediately — will have to be seen as a direct attempt to aid the Russian government in attacking American republic ,” Nadler said in a statement.

House Minority Leader Nancy Pelosi said Mueller's inquiry must be allowed to follow the facts” unhindered by the White House or Republicans in Congress .”

House Speaker Paul Ryan, a Republican, said the proclamation underscored” why we need to follow the facts and work to protect the integrity of future elections .”

” Mueller simply put Moscow on notice, ” said Republican Senator Ben Sasse of Nebraska. “This ought to be a wake-up call to Washington: Putin's shadow war is aimed at undermining Americans' trust in our institutions. We know Russia is coming back in 2018 and 2020. We have to take this threat severely .”