Kaspersky Lab, the Russian cybersecurity firm that the U.S. government has deemed a threat to this country, was the source of tip to the National Security Agency that led to an arrest in what some have said is the largest breach of classified material in U.S. history, Politico reports. The Moscow-based firm reportedly turned the accused, Harold T. Martin III, a former NSA contractor, after receiving strange Twitter messages in 2016 from an account linked to him. Kaspersky’s role in exposing Martin is one of many twists in the case. Martin took home an estimated 50 terabytes of data from the NSA and other government offices over a two-decade period, including some of the NSA’s most sophisticated and sensitive hacking tools, prosecutors said.

The Kaspersky tip is another ironic turn in the Russian company’s saga—and it likely won’t appease detractors who believe it’s a pawn of Russian intelligence. Kaspersky software has been banned from U.S. government computers, though The Daily Beast reported agencies are having difficulties removing it from their networks. “It’s irony piled on irony,” said Stewart Baker, general counsel for the NSA in the 1990s. Martin has been charged with 20 counts of unauthorized and willful retention of national defense information, and is set to go to trial in June.