President Barack Obama’s decision to commute Chelsea Manning’s sentence has ramped up the pressure on WikiLeaks founder Julian Assange to hand himself over to be extradited to the US.

Ms Manning has acknowledged releasing a trove of diplomatic cables and national security documents to WikiLeaks in 2010, embarrassing the US government and its allies.

In a statement after Mr Obama’s decision was made public, Mr Assange called Ms Manning “a hero, whose bravery should be applauded”.

Mr Assange, an Australian journalist and publisher, went on to demand that the US “immediately end its war on whistleblowers and publishers, such as WikiLeaks and myself”.

VICTORY: Obama commutes Chelsea Manning sentence from 35 years to 7. Release date now May 17. Background: https://t.co/HndsbVbRer

— WikiLeaks (@wikileaks) January 17, 2017

Wikileaks’ official account later tweeted Mr Assange was “happy” to go to the US.

“Assange is still happy to come to the US provided all his rights are guaranteed despite White House now saying Manning was not quid-quo-pro,” the tweet read. 

On Twitter last week, Mr Assange’s anti-secrecy site WikiLeaks pleaded with the outgoing US President to free Ms Manning and said such an offer of ”clemency” would persuade him to give up his sanctuary in the Ecuadorian embassy in London.

Mr Assange has been in self-imposed exile at the embassy for more than four years to avoid extradition to Sweden, where he faces sexual assault charges. He could also face possible espionage charges in the US.

Mr Obama used his final hours in the White House to allow Ms Manning, a transgender former Army intelligence analyst who was sentenced to 35 years in prison at Fort Leavenworth, to go free on May 17, nearly 30 years early.

Ms Manning, 29, is among 273 individuals to either be pardoned or receive commutations.

If Obama grants Manning clemency Assange will agree to US extradition despite clear unconstitutionality of DoJ case https://t.co/MZU30SlfGK

— WikiLeaks (@wikileaks) January 12, 2017

“Today, 273 individuals learned that the President has given them a second chance,” wrote Neil Eggleston, Counsel to the President.

“With today’s 209 grants of commutation, the President has now commuted the sentences of 1,385 individuals – the most grants of commutation issued by any President in this nation’s history.”

So much love, so much warmth. >=D https://t.co/ehSDR4n469 #HugsForChelsea

— Chelsea E. Manning (@xychelsea) January 16, 2017

A presidential commutation reduces the sentence being served but it does not change the fact of conviction, whereas a pardon forgives a certain criminal offence.

Ms Manning’s lawyers said she had already served the longest sentence of “any whistleblower in American history”.

After the decision Mr Assange posted: “Thank you to everyone who campaigned for Chelsea Manning’s clemency. Your courage & determination made the impossible possible.”

Fellow whistleblower, former National Security Agency contractor Edward Snowden, also took to Twitter to celebrate the decision to free Ms Manning.

Let it be said here in earnest, with good heart: Thanks, Obama. https://t.co/IeumTasRNN

— Edward Snowden (@Snowden) January 17, 2017

Mr Snowden is living in exile in Russia after leaking state secrets. Russian authorities said on Wednesday that Mr Snowden had been granted a two-year extension to his temporary asylum.

Mr Assange’s lawyer Barry Pollack did not address whether he intended to agree to US extradition, as the WikiLeaks tweet stated.

“For many months, I have asked the DOJ to clarify Mr Assange’s status. I hope it will soon,” Mr Pollack said in the statement.

“The Department of Justice should not pursue any charges against Mr Assange based on his publication of truthful information and should close its criminal investigation of him immediately.”

Another member of Mr Assange’s legal team, Melinda Taylor, insisted previous comments made about the implications of the Manning case still stood. “Everything that he has said he’s standing by,” she said.

With the commutation coming just days before Mr Obama leaves office, any decision on whether to charge or seek to extradite Mr Assange will now fall to the Trump administration.

Mr Trump acknowledged Mr Assange on Twitter earlier this month, using him to cast doubt that Russia was behind the hacking of the Democrats’ emails.

Julian Assange said "a 14 year old could have hacked Podesta" – why was DNC so careless? Also said Russians did not give him the info!

— Donald J. Trump (@realDonaldTrump) January 4, 2017

It was a striking move for the US President-elect to give credibility to Mr Assange, and one that upset many Republicans who see him as an enemy of the US.

When asked about WikiLeaks in the wake of the releases in 2010, Mr Trump had told Fox News’s Brian Kilmeade: “I think it’s disgraceful. I think there should be like death penalty or something.”

Speaking in his last press conference as President on Thursday morning (AEDT), Mr Obama said his decision was justified.

“Let’s be clear, Chelsea Manning has served a tough prison sentence … Justice has been served and a message has still been sent,” Mr Obama said.

“Given she went to trial, that due process was carried out, that she took responsibility for her crime, that the sentence that she received was very disproportionate relative to what other leakers had received and that she had served a significant amount of time, it made sense to commute and not pardon her sentence.”

House Speaker Paul Ryan savaged the move to commute Ms Manning’s sentence.

“This is just outrageous,” he said.

“Chelsea Manning’s treachery put American lives at risk and exposed some of our nation’s most sensitive secrets. President Obama now leaves in place a dangerous precedent that those who compromise our national security won’t be held accountable for their crimes.”

Chelsea Manning's treachery put American lives at risk and exposed some of our nation's most sensitive secrets.

My full statement ↓ pic.twitter.com/PcQrgK2SI3

— Paul Ryan (@SpeakerRyan) January 17, 2017

Senator John McCain was equally unhappy.

“It is a grave mistake that I fear will encourage further acts of espionage and undermine military discipline,” the former presidential candidate said.

“It is a sad, yet perhaps fitting commentary on President Obama’s failed national security policies that he would commute the sentence of an individual that endangered the lives of American troops, diplomats, and intelligence sources by leaking hundreds of thousands of sensitive government documents to Wikileaks, a virulently anti-American organisation that was a tool of Russia’s recent interference in our elections.”

– with ABC