Julian Assange, founder of WikiLeaks, has left the UK after striking a plea deal with the US Department of Justice. Assange, who spent the last 1,901 days in Belmarsh Prison, boarded a flight from Stansted Airport on Monday. The deal requires him to plead guilty to a charge under the Espionage Act for conspiring to unlawfully obtain and disseminate classified national defense information.

The charges stem from WikiLeaks’ publication of hundreds of thousands of classified documents about the Afghanistan and Iraq wars. Assange will make a court appearance on Wednesday in Saipan, located in the Northern Mariana Islands, a US commonwealth. After his plea and subsequent sentencing, which will likely credit the time he served in the UK, Assange is expected to return to Australia.

This plea deal concludes a lengthy legal saga involving Assange’s extradition fight in the UK and his earlier refuge in the Ecuadorian Embassy in London. Assange’s case has been closely followed by international supporters, including advocacy for press freedom and calls from the Australian government for his release.