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Sens. Chuck Grassley and Ron Johnson are demanding FBI agents who provided them with an "unnecessary" briefing in August 2020, alleging they were "advancing Russian disinformation" by investigating Hunter Biden’s business dealings, appear for a transcribed Senate interview next month.

Fox News Digital obtained a letter Grassley, R-Iowa, and Johnson, R-Wis., penned to FBI Intelligence Analyst in Charge Nikki Flores and Deputy Assistant Director for the FBI’s Counterintelligence Division Bradley Benavides on Thursday.

"On August 6, 2020, as we were finishing our September 23, 2020 report on Hunter Biden’s financial connections to foreign governments and questionable foreign nationals, you provided a briefing to us on behalf of the FBI and Intelligence Community," the senators wrote, adding that the briefing was "unnecessary and was only done because of pressure from our Democratic colleagues, including Democratic leadership, to falsely attack our Biden investigation as advancing Russian disinformation."

Johnson and Grassley were working at the time on a joint investigation into Hunter Biden’s role on the board of Ukrainian natural gas firm Burisma Holdings and his "extensive and complex financial transactions."

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Grassley and Johnson reminded the FBI officials that they had already received a briefing from members of the FBI and intelligence community in March 2020, who "provided assurances that there was no reason that our committees should not continue their investigation." 

Hunter Biden

Johnson and Grassley were working at the time on a joint investigation into Hunter Biden’s role on the board of Ukrainian natural gas firm Burisma Holdings and his "extensive and complex financial transactions." (Photo by Teresa Kroeger/Getty Images)

"Nonetheless, the FBI succumbed to the Democratic pressure and provided the infamous August 6, 2020 briefing," they wrote.

The senators said that briefing consisted "primarily of information that we already knew and information unconnected to our Biden investigation." 

"We made clear to you at the briefing that it was not relevant to the substance of our work," they wrote. "In response, you stated that the FBI is not attempting to ‘quash, curtail, or interfere’ in the investigation in any way."

The senators added that they were concerned the briefing could be leaked, and would "shed a false light on the focus of our investigation," noting that did take place, with media reports "falsely" characterized their probe.

Sen. Chuck Grassley

Fox News Digital obtained a letter Grassley, R-Iowa, and Johnson, R-Wis., penned to FBI Intelligence Analyst in Charge Nikki Flores and Deputy Assistant Director for the FBI’s Counterintelligence Division Bradley Benavides on Thursday. (Photo by SUSAN WALSH/POOL/AFP via Getty Images)

"Moreover, whistleblowers have recently alleged that in August 2020, the same month you provided the briefing to us, FBI officials initiated a scheme to downplay derogatory information on Hunter Biden for the purpose of shutting down investigative activity relating to his potential criminal exposure by labeling it ‘disinformation,’" they wrote.

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The senators also noted that the whistleblowers alleged that local FBI leadership "instructed employees not to look at the Hunter Biden laptop immediately after the FBI had obtained it." 

FBI Director Christopher Wray, during Senate testimony earlier this month, said that the whistleblower allegations are "deeply troubling." 

The senators, in their letter, said that they have been requesting "relevant records" related to the Aug. 6, 2020 briefing, but said that the FBI "has consistently failed to respond" to their requests, and failed to provide "those critical records which casts further doubt on the true purpose for the briefing." 

"Simply put, the unnecessary FBI briefing provided the Democrats and liberal media the vehicle to spread their false narrative that our work advanced Russian disinformation," they wrote, adding that the briefing "created interference, which frustrated and obstructed congressional oversight efforts." 

"The FBI answers to Congress and the American people; therefore, we request that you appear before us for a transcribed interview on these and related matters no later than September 8, 2022," they wrote, further requesting that "all records relating to the briefing" be "preserved," as they requested in August 2020.

Republican Wisconsin Sen. Ron Johnson

Sens. Chuck Grassley and Ron Johnson are demanding FBI agents who provided them with an "unnecessary" briefing in August 2020, alleging they were "advancing Russian disinformation" by investigating Hunter Biden’s business dealings, appear for a transcribed Senate interview next month. (Bill Clark/CQ-Roll Call, Inc via Getty Images)

Meanwhile, Grassley and Johnson ultimately released their Hunter Biden interim report in September 2020. 

The 87-page report stated that Obama administration officials "knew" that Hunter Biden’s position on the board of Burisma was "problematic" and that it interfered "in the efficient execution of policy with respect to Ukraine."

Hunter Biden joined Burisma in April 2014 and, at the time, reportedly connected the firm with consulting firm Blue Star Strategies to help the natural gas company fight corruption charges in Ukraine. During the time Hunter Biden was on the board of the company, Joe Biden was vice president and running U.S.-Ukraine relations and policy for the Obama administration.

Grassley and Johnson’s report also revealed that they obtained records from the U.S. Treasury Department that "show potential criminal activity relating to transactions among and between Hunter Biden, his family and his associates with Ukrainian, Russian, Kazakh and Chinese nationals."

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Grassley and Johnson said they received records that Hunter Biden "sent thousands of dollars" to individuals who have "either been involved in transactions consistent with possible human trafficking; an association with the adult entertainment industry; or potential association with prostitution."

"Some recipients of those funds are Ukrainian or Russian citizens," the report states, adding that "the records note that it is a documented fact that Hunter Biden has sent funds to nonresident alien women in the United States who are citizens of Russia and Ukraine and who have subsequently wired funds they have received from Hunter Biden to individuals located in Russia and Ukraine.

"The records also note that some of these transactions are linked to what ‘appears to be an Eastern European prostitution or human trafficking ring,’" the report stated.

Meanwhile, the report states that Senate investigators found millions of dollars in "questionable financial transactions" between Hunter Biden and his associates and foreign individuals, including the wife of the former mayor of Moscow as well as individuals with ties to the Chinese Communist Party.

According to the report, an investment firm co-founded by Hunter Biden, Rosemont Seneca Thornton, "received $3.5 million in a wire transfer" from Elena Baturina, the wife of the former mayor of the Russian capital.

The report went even further and alleged that not just Hunter Biden but other members of the Biden family "were involved in a vast financial network that connected them to foreign nationals and foreign governments across the globe."

Following the 2020 presidential election, Hunter Biden himself revealed he was under federal investigation for his "tax affairs." 

Hunter Biden has been under federal investigation since 2018, a source familiar with the matter told Fox News. 

Fox News has learned that the investigation has now reached a "critical stage," as officials are looking into whether to charge President Biden’s son with various tax violations, possible foreign lobbying violations and more.

Joe Biden's son Hunter's laptop was authenticated by NBC News on May 19

Grassley and Johnson said they received records that Hunter Biden "sent thousands of dollars" to individuals who have "either been involved in transactions consistent with possible human trafficking; an association with the adult entertainment industry; or potential association with prostitution." (Photo by Paul Morigi/Getty Images for World Food Program USA)

A separate source told Fox News that the federal grand jury looking into Hunter Biden’s business dealings wrapped up its latest term late last month but said no charges have been filed.

The investigation is being conducted by Delaware U.S. Attorney David Weiss, a prosecutor appointed by former President Donald Trump.

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The source told Fox News on Wednesday that Weiss and Justice Department officials were looking into whether to charge Hunter Biden with various tax violations and, more seriously, possible foreign lobbying violations. The source said Hunter Biden could face possible false statements charges.

Fox News first reported in December 2020 that Hunter Biden was a subject/target of the grand jury investigation, according to a well-placed government source. According to the source, a "target" means that there is a "high probability that person committed a crime," while a "subject" is someone you "don’t know for sure" has committed a crime."

The federal investigation into Hunter Biden was predicated, in part, by suspicious activity reports (SARs) regarding suspicious foreign transactions.

Another source familiar with the investigation told Fox News in December 2020 that the SARs related to funds from "China and other foreign nations."

A Treasury Department official, who did not comment on the investigation, spoke broadly about SARs, telling Fox News that SARs are filed by financial institutions "if there is something out of the ordinary about a particular transaction." 

The official told Fox News that the mere filing of a SAR does not mean there has been a criminal act or violation of regulations. Instead, it's a flag that a transaction is "out of the ordinary" for the customer. The official noted, though, that an SAR could be part of a money laundering or tax investigation.

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"I take this matter very seriously, but I am confident that a professional and objective review of these matters will demonstrate that I handled my affairs legally and appropriately, including with the benefit of professional tax advisers," Hunter Biden said in December 2020.