Federal prosecutors are seeking the removal of the lead defense lawyer for a Chinese firm charged with bank fraud and sanctions violations, alleging he has a conflict of interest arising from his supervision of a “substantially related” case while he served in a prior position as the Justice Department’s second-highest-ranking official.

James Cole, who was deputy attorney general from 2010 to 2015 in the Obama administration, heads the defense team for Huawei Technologies. The major Chinese telecom equipment-maker was indicted in January on charges of bank fraud, wire fraud, violations of Iran sanctions, and conspiracy to launder money and to obstruct justice.

The high-profile case has drawn much publicity as it is taking place against the backdrop of President Trump’s efforts to seal a trade deal with China and an attempt by his administration to keep Huawei out of the global 5G wireless networks on national security grounds.

In a redacted motion filed Friday in the Eastern District of New York, prosecutors argued that while Cole is defending Huawei, his work in the related investigation, which they did not disclose, “creates the real risk that he will breach his duty of confidentiality to the [Department of Justice] by relying on information he obtained while representing the department.”

Moreover, they said, “there is a risk that Cole will breach his duty of loyalty to the department by making arguments on behalf of the defendants that contradict positions he previously took while representing the DOJ.”

Neither Cole nor his attorney responded to a request for comment.

The move to disqualify is fairly unusual, but analysts note that if the government thinks there is a conflict of interest, prosecutors have an obligation to bring this concern to the court’s attention.

Cole, a partner at the Sidley Austin law firm, informed the Justice Department in January that he was representing Huawei. Later that month, the department informed Cole that he had a conflict of interest in the case, according to the motion.

In a follow-up meeting, Cole and representatives of the Justice Department and the FBI discussed the issue, and after giving Cole a one-day clearance, the government provided him with “privileged and classified” information “in order to have a fulsome discussion,” prosecutors said.

In March, Cole declined to recuse himself, writing to the government that after carefully considering the material, he and his counsel “were unable to determine that I need to be disqualified.”

Later that month, he filed a motion to appear in court for Huawei. And at the first status conference, on April 4, the government said it would not oppose Cole’s motion for the time being. Last week, prosecutors asked the court to remove him.

“It’s a considerable decision to seek to disqualify not just any counsel in a major prosecution like this, but someone of Jim Cole’s pedigree as a former deputy attorney general who clearly has refused to recuse himself,” said David Laufman, a former senior Justice Department official who is now a partner at the law firm of Wiggin and Dana. “But the government clearly feels strongly about its motion and is prepared to litigate its merits.”

While the deputy attorney general oversees a broad range of the department’s most significant cases, he or she does not typically get involved in the day-to-day running of investigations.

“It’s difficult to determine whether the government has a valid argument because of the classified nature of the underlying matter,” said Barbara McQuade, a former U.S. attorney for the Eastern District of Michigan who teaches law at the University of Michigan. “The court will have to review his response and the underlying documents to make a determination.”