A former high-ranking US ambassador is demanding that federal prosecutors explain why he is facing criminal charges for illegal foreign lobbying on Qatar’s behalf while a retired four-star general who collaborated on the effort is not.

The dispute between two Washington power brokers has highlighted the frequently ambiguous boundaries of foreign lobbying laws, as well as what prosecutors claim were high-level, behind-the-scenes influence dealings with the wealthy Persian Gulf country.

Richard G. Olson, former ambassador to the United Arab Emirates and Pakistan, is scheduled to appear in federal court on Friday for a plea hearing on federal charges that include improperly assisting Qatar in influencing US policy in 2017 – when a diplomatic crisis erupted between the gas-rich monarchy and its neighbors over the country’s alleged ties to terror groups and other issues.

Olson has argued that he has a right to know why prosecutors aren’t charging someone he claims he worked alongside in Qatar: retired Marine Gen. John Allen, who led US and NATO forces in Afghanistan before being appointed in late 2017 to lead the influential Brookings Institution think tank.

Allen has denied ever working as a Qatari agent, claiming that his efforts in Qatar in 2017 were motivated by a desire to prevent a Gulf war that would put US troops at risk. On Thursday, his spokesman told The Associated Press that Allen had “voluntarily cooperated with the government’s investigation.”

Olson’s lawyers stated in court papers that he has been seeking a lighter sentence recommendation since 2020 by cooperating extensively with prosecutors “with the express goal” of charging Allen. Prosecutors “reiterated their belief in the strength of their case against” Allen, according to Olson’s lawyers, only to apparently drop their pursuit.

However, at a hearing last week, federal prosecutor Evan Turgeon stated that the government has not “made a prosecutorial decision as to other persons” and disputed how Olson’s attorney described previous discussions. The Justice Department refused to comment on its internal Allen deliberations.

Individuals are prohibited under US law from assisting a foreign entity in influencing US policy without first registering with the Justice Department. The Foreign Agents Registration Act, or FARA, went largely unenforced until prosecutors became more aggressive in recent years.

Typically, FARA violations do not result in significant prison time, but critics of the law argue that there are too many unanswered questions about what constitutes a prosecutable offense.

Notably, Olson was scheduled to plead guilty to violating State Department policy by working for a foreign government within a year of leaving government service, rather than a FARA violation.

Last week, Olson’s lawyer stated in court that federal prosecutors made it clear that they were pursuing a FARA case against Allen. Prosecutors said in court filings that Olson recruited Allen to help him “provide aid and advice to Qatari government officials with the intent to influence US foreign policy” shortly after the Gulf diplomatic crisis erupted in June 2017.

During President Donald Trump’s administration, the crisis sparked a heavy spending war between Qatar and rivals Saudi Arabia and the UAE in a battle for influence in Washington.

Imaad Zuberi, a one-time political donor who is currently serving a 12-year prison sentence on corruption charges and who prosecutors say illegally lobbied for Qatar, paid Olson $20,000 per month.

Prosecutors stated in Olson’s plea agreement that Zuberi agreed to pay Allen an undisclosed fee for his efforts. According to Allen’s spokesman, the general was never paid.

Prosecutors said Allen met with Olson and Zuberi in a Washington hotel in mid-June 2017 to explain “how he would conduct the lobbying and public relations campaign.”

Several days later, Olson and Allen flew to Qatar at Zuberi’s expense to meet with Qatar’s ruling emir and other government officials, where they explained that they were not representing the US government but “noted that they had the connections with US government officials that placed them in a position to help Qatar,” according to prosecutors.

Allen advised the Qataris on what steps to take, including signing a pending deal to purchase F-15 fighter jets and using e a major U.S. military base in Qatar “as leverage to exert influence over U.S. government officials,” prosecutors wrote.