A former press secretary for Bill Clinton lashed out on Twitter Thursday, after a report this week revealed the existence of an FBI criminal investigation into a Russian nuclear energy company that the Obama administration allowed the sale of uranium assets to in 2010.

Angel Ureña attacked Peter Schweizer, president of the Government Accountability Institute and author of Clinton Cash, who had reported extensively and exclusively on then-Secretary of State Hillary Clinton and former President Bill Clinton’s relationship to the deal during the 2016 elections.

Schweizer, also a senior editor-at-large at Breitbart News, posted a link to a Daily Mail story reporting that the Senate Judiciary Committee was looking into potential “conflicts of interest” of Hillary Clinton over the deal.

Urena tweeted to Schweizer, attacking the accuracy of Schweizer’s book. Schweizer shut him down: “Ur boss hid U1 donations. Issue now w @FBI, not me. Have fun.”

Here is the whole exchange:

@angelurena not true. Quality of work confirmed by NYT, WaPo, ABC News, etc. Ur boss hid U1 donations. Issue now w @FBI, not me. Have fun — Peter Schweizer (@peterschweizer) October 19, 2017

Spelling and footnotes. Nice try. NYT 4K word frnt pg story on U1 story-confirms everything. U forget? Secret donors https://t.co/6YiBi8EGAj — Peter Schweizer (@peterschweizer) October 19, 2017

Urena then attacked Trump for mentioning the Uranium One deal, and retweeted quotes from a speech by former President George W. Bush delivered on Wednesday.

While Trump has spent the day peddling a debunked lie, here’s a reminder that the @ClintonFdn is helping to try to curb the opioid epidemic. https://t.co/yLOZa1D1Ei — Angel Ureña (@angelurena) October 19, 2017

Earlier this week, The Hill revealed that the FBI had gathered “substantial evidence that Russian nuclear industry officials were engaged in bribery, kickbacks, extortion and money laundering designed to grow Vladimir Putin’s atomic energy business inside the United States.”

Federal agents used a confidential U.S. witness working inside the Russian nuclear industry to gather evidence as early as 2009 that showed Moscow had compromised an American uranium trucking firm with bribes and kickbacks in violation of the Foreign Corrupt Practices Act, The Hill reported.

They also obtained an eyewitness account from an American businessman and FBI informant that indicated Russian nuclear officials had routed millions of dollars to the U.S., designed to benefit former President Clinton’s charitable foundation when then-Secretary Clinton served on a committee that allowed for a controversial deal favorable to Russia to go through.