Manning has been a focus of a worldwide debate on government secrecy since she provided more than 700,000 documents, videos, diplomatic cables and battlefield accounts to the anti-secrecy group WikiLeaks – a leak for which she was sentenced to serve 35 years in prison.

Manning, formerly known as US Army Private First Class Bradley Manning, was born male but revealed after being convicted of espionage that she identifies as a woman.

Manning, who is held at the Fort Leavenworth, Kansas, military prison, accepted responsibility for leaking the material, and has said she was confronting gender dysphoria at the time of the leaks while deployed in Iraq. Her sentence will now expire on May 17, the White House said.

Manning was working as an intelligence analyst in Baghdad in 2010 when she gave WikiLeaks a trove of diplomatic cables and battlefield accounts that included a 2007 gunsight video of a US Apache helicopter firing at suspected insurgents in Iraq, killing a dozen people including two Reuters news staff.

Her attorney had argued her sentence exceeded international legal norms, and she has twice attempted suicide.

House Speaker Paul Ryan said the decision to commute Chelsea Manning’s sentence was “just outrageous”.

Ryan says Manning “put American lives at risk and exposed some of our nation’s most sensitive secrets”.

He says Obama is setting “a dangerous precedent that those who compromise our national security won’t be held accountable for their crimes.”

WikiLeaks says Obama may have saved Manning’s life by granting her clemency.

In a tweet soon after the announcement, WikiLeaks founder Julian Assange thanked “everyone who campaigned for Chelsea Manning’s clemency. Your courage & determination made the impossible possible.”

Assange didn’t mention his earlier pledge that he would agree to US extradition if Obama granted clemency to Manning. – AAP

Chelsea Manning: Traitor or humanist?

Chelsea Manning has always considered herself an advocate for transparency.

As a US solider working in Iraq, Manning was disturbed by the inhumanity of US military actions. This led to her decision to steal hundreds of thousands of secret government files and give them to the internet whistle blower WikiLeaks.

Those actions in 2010 led to a high-profile court martial that ended with Manning’s conviction on 19 of 21 counts, but not the most serious charge of aiding the enemy. In August 2013, Manning was sentenced to 35 years in prison.

Manning is serving her sentence in a military prison at Fort Leavenworth military base in the US state of Kansas.

Soon after being sentenced, Manning, now 29, announced intentions to undergo gender reassignment and live as a woman. Formerly known as Bradley Manning, Chelsea Manning soon found herself in another conflict with the military over this desire.

In September she ended a hunger strike after reaching agreement over her desire to undergo gender reassignment surgery.

Manning’s case made her a cause celebre of free information advocates. She had admitted to gathering the documents while working as an intelligence analyst in Iraq.

Manning has said she considers herself neither a pacifist nor a conscientious objector.

In a 2013 letter to Britain’s Guardian newspaper Manning said she had never claimed to be anti-war and noted that she joined the military to defend her country.

She described herself as a humanist motivated in her actions not only by her belief in transparency, but also by deep concern for the value of human life.

She stressed her convictions in a statement reacting to being named the 2013 recipient of the Sean MacBride Peace Award.

“The public cannot decide what actions and polices are or are not justified if they don’t even know the most rudimentary details about them and their effects,” she wrote.

The document cache Manning released to Wikileaks included hundreds of thousands of US diplomatic cables, assessment files of detainees held at Guantanamo Bay, Cuba, and logs of military incident reports from Iraq and Afghanistan. It was the largest-ever leak of government secrets in US history.

During the trial the prosecution painted Manning as a traitor whose actions endangered the lives of US military personnel and people who had associated with the US military. The defence on the other hand called her a well-intentioned individual trying to reveal the true face of war.

Manning had access to the documents while working as a military analyst in Iraq, a job she was assigned to in 2009.

The prosecution charged that Manning disregarded superiors, broke an oath not to release secrets and disregarded the danger created by releasing the data.

Prosecutors said Manning systematically harvested information and dumped it onto the internet and the hands of the enemy and attempted to cover up the actions. They sought a sentence of life in prison on the most serious charge of aiding the enemy.

Attorney David Coombs described Manning as “young, naive and well-intentioned.” She was only 22 at the time and did not intend to aid the enemy, Coombs argued, saying Manning only intended to inform Americans about what its military was doing in Iraq.

Coombs said Manning hoped that if the US public knew the full story of what was happening in Iraq, it could change the way people thought about the war.

– DPA