The Justice Department has declined to provide a clear explanation as to why a well-known Russian hacker was released home last year amid warnings from President Joe Biden that the Kremlin may soon carry out cyberattacks against the United States.

Aleksei Burkov is a cybercriminal who ran two noted underground hacking operations. After he was arrested by Israeli law enforcement in 2015, the Kremlin put a lot of effort into stopping him from being extradited to the U.S. Burkov eventually arrived in the U.S. in 2019, where he pleaded guilty to a host of crimes and received a nine-year sentence, though given credit for the time spent in Israeli prison.