WASHINGTON (AP) — The Justice Department is moving to drop charges against two Russian companies that were accused of funding a social media campaign to sway American public opinion during the 2016 U.S. presidential election.

Prosecutors said they concluded that a trial, against a corporate defendant with no presence in the United States and no prospect of meaningful punishment even if convicted, would likely expose sensitive law enforcement tools and techniques, "potentially undermining their effectiveness."

Concord Management and Consulting LLC and Concord Catering were among three companies and 13 individuals charged in 2018 by special counsel Robert Mueller in a conspiracy to spread disinformation on social media during the 2016 presidential race. The effort was aimed at dividing American public opinion and sowing discord in the electorate, officials said.

The case was one of the signature indictments from Mueller's two-year Russia investigation. Together with a separate case against Russian government hackers accused of breaking into Democratic email accounts, it revealed a sweeping Russian effort to influence, or interfere in, the race between Republican Donald Trump and Democrat Hillary Clinton.

Concord was the sole defendant in the case to enter an appearance in Washington's federal court and contest the allegations. The case had been set for trial next month, making the government's filing all the more abrupt.

Concord is controlled by Yevgeny Prigozhin, a wealthy businessman known as "Putin's chef" for his ties to Russian President Vladimir Putin. He has been hit with U.S. sanctions over Russian interference in the 2016 election and is charged alongside his company in the indictment brought by Mueller.

The company, with the help of a high-powered law firm, filed a series of motions over the last two years, including to dismiss charges and to exclude certain evidence from the case.

In January 2019, prosecutors alleged that confidential material from the Russia investigation, which had been handed over to defense attorneys for Concord, was altered and disseminated as part of a disinformation campaign aimed at discrediting the special counsel's Russia investigation. The files surfaced online in a link posted by a pro-Russia Twitter account. But the Justice Department stopped short of accusing Concord of leaking the material.

Still, prosecutors argued that the company's request to have sensitive new evidence sent to Russia "unreasonably risks the national security interests of the United States."

Some of the court appearances in the case have been unusually contentious, with the federal judge overseeing it chastising a lawyer for Concord, Eric Dubelier, for references in court filings to Looney Tunes and the 1978 raunchy comedy "Animal House" to criticize the Mueller investigation.

"I'll say it plain and simply: Knock it off," U.S District Judge Dabney Friedrich told Dubelier at a January 2019 court appearance.

Dubelier, who has referred to the case as involving a "made up" crime, has made allegations of prosecutorial misconduct and even once accused the judge of bias. The judge rejected the allegation.

But with the case approaching trial, prosecutors said they had to weigh the risk of potentially exposing sensitive national security information against the benefits of continuing with the case against a company that likely wouldn't face any significant punishment in the U.S.

In the court filing on Monday, prosecutors said Concord had been "eager and aggressive in using the judicial system to gather information about how the United States detects and prevents foreign election interference."

"In short, Concord has demonstrated its intent to reap the benefits of the Court's jurisdiction while positioning itself to evade any real obligations or responsibility," prosecutors wrote. "It is no longer in the best interests of justice or the country's national security to continue this prosecution."

Concord Catering did not have attorneys appear in court, but prosecutors said they would seek to drop charges against that company as well because it too was controlled by Prigozhin and "based on the likelihood that its approach to litigation would be the same as Concord."

Prosecutors vowed to continue to pursue their case against the 13 Russians who were named in Mueller's indictment, along with the troll farm that Concord was alleged to have funded, the Internet Research Agency.