Barack Obama vows to speak out on 'core values' after he leaves office

President Barack Obama vowed that he would not fade into the background once he leaves office and promised to speak out whenever he feels America’s “core values” are threatened.

While he said that he was looking forward to taking a break from politics, he told his final news conference as president that “certain issues or certain moments where I think our core values may be at stake”, would draw him out of retirement.

“I put in that category if I saw systematic discrimination being ratified in some fashion,” he said. “I put in that category explicit or functional obstacles to people being able to vote, to exercise their franchise. I put in that category institutional efforts to silence the press.”

In a clear differentiation to his successor Donald Trump who has threatened to deport undocumented migrants and their children, Mr Obama said he would speak out if efforts were made “to round up kids who have grown up here and for all practical purposes are American kids and send them somewhere else, when they love this country.”

Mr Obama also revealed his advice to Mr Trump.

"This is a job of such magnitude that you can't do it by yourself," Mr Obama said. "Reality has a way of biting back."

The outgoing leader also defended as “entirely appropriate” his decision to commute the sentence of Chelsea Manning.

He said 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. “Let’s be clear. Chelsea Manning has served a tough prison sentence.”

Rejecting critics who argued his action would encourage espionage and future leaks of classified information, he said: “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.”

Mr Obama also urged Mr Trump to keep separate the issue of economic sanctions on Russia from the pursuit of talks to reduce nuclear stockpiles.

The President-elect has said that he would propose offering to end sanctions on Moscow in return for a nuclear arms reduction deal.

But Mr Obama, whose administration imposed the sanctions in 2014 after Russia's annexation of the Crimea peninsula from Ukraine, said: "Russia continues to occupy Ukrainian territory and meddle in Ukrainian affairs.”

He added: "I think it would probably best serve, not only American interests, but also the interests of preserving international norms if we made sure that we don't confuse why these sanctions have been imposed with a whole set of other issues.

"It is important for the United States to stand up for the basic principal that big countries don't go around and invade and bully smaller countries.”

Sharing thoughts on his future plans, he said it was important for him to “take some time to process this amazing experience that we've gone through, to make sure that my wife with whom I will be celebrating a 25th anniversary this year, is willing to re-up and put up with me for a little bit longer.”

He added: "I want to spend precious time with my girls."

Casting his daughters Sasha and Malia as the source of his hope and as America's future, he said that although they were disappointed by Mr Trump's victory over Democratic Party rival Hillary Clinton, they did not "mope".

He said: "We've tried to teach them hope.”

He also voiced a belief that the world could get better.

He said: "I believe in this country and I believe in the American people. I believe that people are more good than bad.

"I believe tragic things happen, I think there's evil in the world but I think at the end of the day, if we work hard, and if we're true to those things in us that feel true and feel alright, that the world gets a little better each time."