Barack Obama has defended as “entirely appropriate” his decision tocommute the sentence of Chelsea Manning, arguing that the whistleblower behind one of the largest breaches of classified information in US history had served a tough but adequate prison sentence.

“I feel very comfortable that justice has been served,” Obama told reporters at his final White House press conference on Wednesday, when asked about his move a day prior to commute the sentence handed down to Manning in 2013.

“Let’s be clear: Chelsea Manning has served a tough prison sentence,” Obama said, while rejecting critics who argued his action would encourage espionage and future leaks of classified information.

“The notion that the average person who is thinking about disclosing vital classified information would think that it goes unpunished … I don’t think would get that impression from the sentence that Chelsea Manning has served.”

Manning, a former intelligence analyst in Iraq, was arrested seven years ago for leaking more than 700,000 diplomatic cables, videos and documents to WikiLeaks that exposed the nature of the wars in Iraq and Afghanistan.

A transgender woman, she was convicted in 2013 by a military court and has been serving her sentence at a male military prison in Fort Leavenworth, Kansas. Obama’s unexpected act to commute her sentence in the final days of his presidency means Manning will now walk free on 17 May.

Obama said Manning’s 35-year prison sentence was “very disproportionate relative to what other leakers have received”, while adding that “a message has still been sent” that appropriate channels should be used to raise concerns about the actions of the government.

“It has been my view that given she went to trial, that due process was carried out, that she took responsibility for her crime … and that she had served a significant amount of time,” Obama said. “That it makes sense to commute – and not pardon – her sentence.”

Manning’s defense lawyer at her military trial, David Coombs, said that Obama’s commutation would put out a positive message. “It gives the message that we will value the people who bring important information into the public domain and that we will take into account their reasons for doing so.”

Coombs said that the soldier’s 35-year sentence was an injustice. “She was trying to do what’s right – she didn’t want to harm the US. You give a 35-year sentence to someone who is a traitor or a spy, and Chelsea was neither of those things.”

Earlier on Wednesday, Vice President-elect Mike Pence stepped up the Republican backlash to the commutation, calling it bluntly a “mistake”. Pence said that by leaking 750,000 US documents in 2010, Manning had “compromised our national security, endangered American personnel downrange, compromised individuals in Afghanistan who were cooperating with our forces”.

He added: “Private Manning is a traitor and should not have been turned into a martyr.”

The incoming vice-president and other senior Republicans’ strident criticism raises the prospect that the new administration of Donald Trump, which starts on Friday at noon, will try to overturn Manning’s commutation and keep her in military prison on her 35-year sentence. Under the terms of Obama’s order, the soldier must remain imprisoned for the next 120 days, which would give Trump and his choice of US attorney general, Jeff Sessions, four months to try to undo it.

But legal experts with knowledge of the executive power of commutations and pardons said that as the law stood, an outgoing president could not be overridden by their successor. “Obama’s decision to commute has already been made, and will be treated as in effect even after Trump takes office,” said Dr Jeffrey Crouch of American University, author of The Presidential Pardon Power.

Crouch said that “once clemency is offered, delivered and accepted, pretty much everyone acknowledges that it’s irreversible. There doesn’t seem to be any dispute about those three steps here.”

Professor Mark Osler, a commutation law expert at the University of St Thomas in Minnesota, agreed that “once a decision is made by a president it cannot be revisited”.

The president’s decision to grant clemency to Manning comes as his administration has accused Russia of interfering with the US election by hacking into the emails of Democrats and Hillary Clinton’s campaign manager and releasing the content to WikiLeaks in an attempt to help Donald Trump.

Obama said he did not see a contradiction between the two issues, noting the findings by the US intelligence community were not conclusive with respect to “whether WikiLeaks was witting or not in being the conduit” for Russia’s plot.

He also declined to weigh in on an offer by the WikiLeaks founder Julian Assange to face extradition to the US in the wake of the Manning commutation. “I don’t pay a lot of attention to Mr Assange’s tweets,” Obama said, referring the matter to the Department of Justice.

“What I can say broadly is that in this new cyber age, we’re going to have to make sure that we continually work to find the right balance of accountability and openness and transparency that is the hallmark of our democracy, but also recognize that there are adversaries and bad actors out there who want to use that same openness in ways that hurt us.”

(Published 2017/01/02 at 12:29 am)