A British High Court ruled Friday that WikiLeaks founder Julian Assange can be extradited to the United States to face charges of violating the Espionage Act.

The 50-year-old Australian will remain in London’s Belmarsh prison, where he has been held since April 2019 after the Ecuadoran Embassy revoked his political asylum.

Stella Moris, Assange’s partner, mother of his two children and his former lawyer, said they will file a final appeal to the British Supreme Court, which would hear the case only if the court believes it involves a point of law “of general public importance.” That process could take weeks or months.

If the British Supreme Court court declines to hear Assange’s final appeal, he could seek a stay of extradition from the European Court of Human Rights — which Britain is still subject to — a substantial legal hurdle.

The High Court ruling on Friday brings Assange one step closer to being turned over to U.S. marshals for a flight to Washington, where he would stand trial in federal court in Northern Virginia.

U.S. prosecutors charge that Assange helped hack into classified information and published thousands of pages of military records and diplomatic cables about the wars in Afghanistan and Iraq, which put the lives of allies in danger.

Assange’s supporters say he was acting as an investigative journalist who uncovered a trove of damning material about American acts abroad. They say the extradition and prosecution will undermine press freedoms in the United States.

“How can it be fair, how can it be right, how can it be possible, to extradite Julian to the very country which plotted to kill him?” Moris said, in reference to a Yahoo News report that members of the Trump administration discussed kidnapping Assange or having him assassinated.

“We will appeal this decision at the earliest possible moment,” Moris said.

In January, a British judge ruled that Assange should not be extradited to the United States because he would be at high risk of suicide.

The U.S. government appealed that decision, suggesting the psychiatrist who examined him was biased and that Assange’s mental health was not a barrier to extradition.

Assange was charged under the Trump administration with violating the Espionage Act, the first time U.S. federal prosecutors have targeted not just the source but the publisher of classified information.

Chelsea Manning, the Army private who shared secret diplomatic and military information with WikiLeaks in 2010, was released from prison under President Barack Obama but spent roughly a year in jail for refusing to testify before a grand jury investigating Assange.

Under President Biden, the Justice Department assured the British courts that Assange can be put on trial in the United States despite his mental health issues.

If he were convicted, the U.S. government in October promised the British courts that Assange would not be sent to the country’s highest-security prison or automatically placed in solitary confinement. He could also seek to serve his sentence in his native Australia.

The British High Court sided with the Americans, and Judge Timothy Holroyde said the assurances offered over the conditions of Assange’s incarceration in the United States were both “sufficient” and “solemn undertakings,” promised from one government to another.

Assange’s defense attorneys maintained the U.S. assurances could not be trusted.

“It is highly disturbing that a U.K. court has overturned a decision not to extradite Julian Assange, accepting vague assurances by the United States government, which has reportedly plotted to kidnap or even assassinate Mr. Assange, that if Mr. Assange is extradited he will be provided appropriate care and not be held in a super-maximum facility,” U.S.-based defense attorney Barry Pollack said.

By the time he was charged in the United States under seal in 2017, Assange had already spent six years living in Ecuador’s London embassy out of fear that he would be extradited to Sweden for a sexual assault investigation and ultimately to the United States. The Ecuadoran government expelled him in 2019, and he was promptly arrested by British authorities.

The Justice Department began investigating Assange in 2010 but under Obama decided that any prosecution would create a dangerous precedent that could be used to go after news organizations. The Espionage Act has been used to prosecute government employees and contractors who share classified information with the press, but never before against the publisher of that information.

In their indictment of Assange, prosecutors took pains to distinguish him from traditional journalists, saying that he had encouraged illegal hacking and recording for personal reasons, and knowingly put people at risk by publishing their names.

“The Department takes seriously the role of journalists in our democracy,” then-Assistant Attorney General for National Security John Demers said at a press conference in 2019. “It is not and has never been the Department’s policy to target them for their reporting. Julian Assange is no journalist.”

Press freedom groups dismissed those distinctions as insufficient protection for journalists.

“We continue to have profound concerns about the press-freedom implications of this prosecution,” Jameel Jaffer, executive director at the Knight First Amendment Institute at Columbia University, said in a statement Friday. “The Trump administration should never have filed this indictment, and we call on the Biden administration again to withdraw it.”

The group Reporters Without Borders also condemned the decision that Assange can be extradited, saying he would face possible life imprisonment “for publishing information in the public interest.”

The group called for the U.S. government “to drop its more than decade-long case against him once and for all,” in line with its commitment to protect media freedom.