Julian Assange has been released from British prison, according to WikiLeaks, the organisation he founded, which posted on social media a video of him boarding a flight that departed the UK at London’s Stansted airport on Monday evening. The announcement that Assange was free came shortly after news broke that he was set to plead guilty this week to violating US espionage law, in a deal that would allow him to return home to his native Australia. US prosecutors said in court papers that Assange, 52, has agreed to plead guilty to a single criminal count of conspiring to obtain and disclose classified US national defence documents, according to filings in the US district court for the Northern Mariana Islands. Assange is due to be sentenced at a hearing on the island of Saipan in the Northern Mariana Islands at 9am local time on Wednesday (11pm GMT on Tuesday). Under the deal, which must be approved by a judge, he is likely to be credited for the five years he has already served and face no new jail time. In a letter to a federal judge in the district court for the Northern Mariana Islands, a senior justice department official said that he was being sent to Saipan because of its “proximity to the defendant’s country of citizenship”. The official added that once the sentencing hearing was completed, Assange was expected to travel on to Australia. WikiLeaks said on X that Assange had left Belmarsh prison on Monday morning, after 1,901 days of captivity there. He had spent the time, the organisation said, “in a 2x3 metre cell, isolated 23 hours a day”. Assange was set to be reunited with his wife, Stella, who confirmed on X that “Julian is free!”. She thanked Assange’s supporters, saying “Words cannot express our immense gratitude to YOU- yes YOU, who have all mobilised for years and years to make this come true”. In the WikiLeaks video, Assange, looking healthy dressed in a shirt and jeans with his white hair cut short, is seen climbing the stairs into a plane. WikiLeaks in 2010 released hundreds of thousands of classified US military documents on Washington’s wars in Afghanistan and Iraq – the largest security breaches of their kind in US military history – along with swaths of diplomatic cables. An Australian government spokesperson did not confirm or deny the plea deal but said Canberra was “aware” of the legal proceedings, adding: “prime minister [Anthony] Albanese has been clear – Mr Assange’s case has dragged on for too long and there is nothing to be gained by his continued incarceration.” Assange’s mother Christine welcomed the developments, saying “I am grateful my son’s ordeal is finally coming to an end.” The plea agreement comes months after the US president, Joe Biden, said he was considering a request from Australia to drop the US push to prosecute Assange. Assange was indicted during the former president Donald Trump’s administration over WikiLeaks’ mass release of secret US documents, which were leaked by Chelsea Manning, a former US military intelligence analyst who was also prosecuted under the Espionage Act. Many press freedom advocates have argued that criminally charging Assange represents a threat to free speech. In a court document filed with the US district court for the Northern Mariana Islands ahead of Wednesday’s sentencing, the US government laid out the details of the charge of conspiracy to obtain and disclose national defense information that lies at the heart of the plea deal. It accuses Assange of “knowingly and unlawfully” conspiring with the US army intelligence analyst Chelsea Manning to “receive and obtain documents, writings, and notes connected with the national defense … up to the SECRET level”. As news of the plea deal spread on Monday night, there were widespread expressions of relief that Assange’s years-long captivity appeared to be coming to an end. But there were also concerns that a conviction, even on a single count, could have a devastating and prolonged impact on investigative and national security journalism. Jameel Jaffer, executive director of the Knight First Amendment Institute at Columbia University which defends press freedom, said that the plea deal averted the worst-case scenario of a full-on prosecution. “But this deal contemplates that Assange will have served five years in prison for activities that journalists engage in every day.” Jaffer warned that the outcome could “cast a long shadow over the most important kinds of journalism, not just in this country but around the world”. Meanwhile Mike Pence, the former US vice-president, criticised the deal, saying it was a “miscarriage of justice”. Writing on X he said: “There should be no plea deals to avoid prison for anyone that endangers the security of our military or the national security of the United States. Ever.” Assange was first arrested in Britain in 2010 on a European arrest warrant after Swedish authorities said they wanted to question him over sex-crime allegations that were later dropped. He fled to Ecuador’s embassy, where he remained for seven years, to avoid extradition to Sweden. He was dragged out of the embassy in 2019 and jailed for skipping bail. He has been in London’s Belmarsh top security jail ever since, from where he has been fighting extradition to the US. While in Belmarsh, Assange married his partner Stella with whom he had two children while he was in the Ecuadorian embassy. Manning was sentenced to 35 years in prison after being convicted of violating the Espionage Act and other offences for leaking classified government and military documents to WikiLeaks. President Barack Obama commuted her sentence in 2017, allowing her release after about seven years behind bars.