Don’t seek to wreck liberal world order, Obama warns Trump

US President Barack Obama made a strident case for his successor Donald Trump to retain America's support for a liberal world order on Sunday, warning world peace and prosperity depend on it.

"The main advice that I give to the incoming president is the United States really is an indispensable nation in our world order," Obama said in Peru as he wrapped up his final foreign visit.

The United States' ability to uphold "international norms and rules …that's what's made the modern world," Obama said, admitting that Washington had not always fulfilled its own ideals, but remained vital to global security.

"Here in Latin America there's been times when countries felt disrespected and on occasion had cause for that."

But he argued history served as a warning for those imagining or flirting with a revised global order.

"Take an example like Europe before that order was imposed. We had two world wars in a span of 30 years. In the second one, 60 million people were killed. Not half a million, not a million but 60 million. Entire continents in rubble."

"We're not going to be able to handle every problem, but the American president and the United States of America, if we're not on the side of what's right, if we're not making the argument and fighting for it even if sometimes we're not able to deliver it 100 percent everywhere, then it collapses."

"There's nobody to fill the void. There really isn't," he said.

Obama said he doesn't intend to become his successor's constant critic - but reserved the right to speak out if President-elect Donald Trump or his policies breach certain ''values or ideals''.

Offering a rare glimpse into his thoughts on his post-presidency, Obama suggested once he was out of office he would uphold the tradition of ex-presidents stepping aside quietly to allow their successors space to govern. He heaped praise on his predecessor George W Bush, saying he ''could not have been more gracious to me when I came in'' and said he wanted to give Trump the same chance to pursue his agenda ''without somebody popping off'' at every turn.

But Obama suggested there may be limits to his silence. ''As an American citizen who cares deeply about our country, if there are issues that have less to do with the specifics of some legislative proposal or battle or go to core questions about our values and ideals, and if I think that it's necessary or helpful for me to defend those ideals, I'll examine it when it comes,'' Obama told reporters.

Yet Obama suggested that while he might not always hold his tongue, his goal wasn't to spend his time publicly disparaging his replacement.

''My intention is to, certainly for the next 2 months, just finish my job,'' Obama said. ''And then after that, to take Michelle on vacation, get some rest, spend time with my girls, and do some writing, do some thinking.''