Chelsea Manning, the U.S. whistleblower and activist responsible for releasing military documents to WikiLeaks, said she’s been subpoenaed to testify before a grand jury — and she doesn’t know why.

Manning, whose 35-year sentence was commuted by President Barack Obama after seven years, told the New York Times she received a notice to appear on March 5. She said she intends to fight the subpoena by arguing that it violates her constitutional rights, although she declined to say if she would comply.

“Given what is going on, I am opposing this,” she said. “I don’t know the parameters of the subpoena apart from that I am expected to appear. I don’t know what I’m going to be asked.”

But Manning and her attorneys suspect the subpoena is connected to WikiLeaks founder Julian Assange.

The subpoena was issued by the Eastern District of Virginia, the same U.S. district where Assange has been secretly charged by American prosecutors. Attorneys mistakenly revealed that Assange was in legal trouble under seal in an unrelated court filing last November.

Manning was serving jail time on numerous espionage charges after releasing a cache of military documents to WikiLeaks, including a video that showed a 2007 U.S. airstrike in Baghdad that killed two dozen people. Two Reuters journalists were killed in the blast, raising questions about potential war crimes committed in the region by the U.S.

Assange has been holed up in an Ecuadorian embassy in London for years to avoid prosecution over publishing of thousands of sensitive documents through WikiLeaks.