By Agencies

Ex-US army private, who leaked 700,000 classified military and diplomatic documents to WikiLeaks, is set to leave jail.

Chelsea Manning, the transgender army private jailed for one of the largest leaks of classified documents in US history, was released from a military prison on Wednesday after seven years behind bars.

In July 2010, Manning - then a male soldier known as Bradley - was arrested over the release of a huge trove of more than 700,000 classified military and diplomatic documents via the anti-secrecy website WikiLeaks.

On Wednesday, Manning left the prison barracks at Fort Leavenworth in Kansas - the only maximum-security facility run by the Pentagon - thanks to a commutation of her sentence by ex-President Barack Obama before he left office.

Without Obama's parting gift, Manning, who served as an intelligence official in Iraq, would have remained behind bars until 2045, after serving a 35-year sentence.

Supporters of Manning - who attempted suicide twice last year alone - said they feared she would not have been able to survive the long sentence. Now, she can complete her transition as a free, openly transgender woman.

First steps of freedom!! https://t.co/kPPWV5epwa#ChelseaIsFree pic.twitter.com/0R5pXqA1VN

— Chelsea Manning (@xychelsea) May 17, 2017

"Two more days until the freedom of civilian life," Manning tweeted on Monday. "Now hunting for private #healthcare like millions of Americans."

Manning, now 29, also went on a hunger strike during her detention to denounce the disciplinary measures to which she was subjected - including stints in solitary confinement.

"For the first time, I can see a future for myself as Chelsea. I can imagine surviving and living as the person who I am and can finally be in the outside world," she wrote last week.

Chase Strangeo, a lawyer with the American Civil Liberties Union, said: "Chelsea Manning is just this exceptional human being who continued to see the goodness even in the face of horrible evidence to the contrary."

Manning's defence team is intent on protecting her, while the military is keen on keeping her release low-key. No press conference is planned and media massing at the military installation may be hard-pressed to even catch a glimpse of Manning.

"To ensure the privacy and security of Inmate Manning, no further information concerning the release will be provided," US Army spokesman Dave Foster said in a statement.

Virtually unknown at the time of her arrest, Manning today is a well-known figure around the world.

Labelled a traitor by right-wing President Donald Trump, she has gained the support of celebrities and is seen by many Americans as a courageous rights activist who was handed an unfair sentence for revealing civilian deaths caused by US bombings in Iraq and Afghanistan.

She was not able to flee abroad like Edward Snowden, who in 2013 released documents showing that the NSA was sweeping up US citizens' communications metadata.

Ahead of Manning's release, a group of musicians released a compilation album with all proceeds to go to the former soldier as she starts a new life.

"Hugs for Chelsea," a digital album available for a $25 donation, features tracks by artists known for their left-wing activism, including Rage Against the Machine guitarist Tom Morello and Sonic Youth co-founder Thurston Moore.

Transitioning behind bars

Manning has also surreptitiously become an icon for transgender activists.

She was able to start hormonal treatment in prison to begin transitioning toward her female identity. This transition is certain to speed up outside a prison environment Manning said denied her "right to exist". 

While Manning's sentence was commuted, her conviction remains intact. Manning, who will turn 30 in December, has appealed.

She is also still employed by the army, and retains its insurance coverage.

"Manning is statutorily entitled to medical care while on excess leave in an active duty status, pending final appellate review," said Foster, the army spokesman.

Chase Madar, Manning's biographer, argued that she carried out an act of public service by leaking the documents, adding that none of the information leaked by Manning was top secret.

"One disturbing thing is just how few people leaked," Madar said. "Why was Chelsea Manning the first one? If hundreds of thousands of people had access to the material ... no one had the guts?"