KIEV, Nov. 20 - U.S. President Barack Obama, who briefly met Russian President Vladimir Putin at a summit in Peru on Sunday, said he wants to reach a negotiated peace settlement in Ukraine before he leaves office in January.

Obama, during a wide-ranging press conference on the sidelines of the Asia-Pacific Economic Cooperation (APEC) summit, also criticized Iran and Russia's role in Syria’s brutal civil war.

Obama said he talked with Putin on November 20 about Ukraine and the "need for us to get things done."

"I urged him to instruct his negotiators to work with ourselves, with France, with Germany, with Ukraine to see if we can get that done before my term is up," Obama said, Radio Free Europe/Radio Liberty reported.

A White House statement said Obama told Putin U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov should continue meeting on various issues to stem international violence and ease the suffering of the Syrian people.

The White House said the meeting between Obama and Putin was informal. Relations between the two have been strained, exacerbated by the situation in Syria and Russia ’s seizure of the Crimea from Ukraine in 2014.

Obama urged Putin to adhere to the Minsk agreements to stop the fighting in the Donetsk and Luhansk regions of Ukraine where Russia has been accused of backing dissident groups, supplying arms and military advice.

Moscow has backed pro-Russia separatists fighting government forces in eastern Ukraine, where the conflict has killed nearly 10,000 people.

U.S. President-elect Donald Trump's shock election victory has been met with trepidation in Kiev because of the billionaire's praise for Putin.

Obama also said he was "not optimistic" about the immediate future of Syria, where government forces backed by Russian warplanes have been bombarding rebel-held parts of the northern city of Aleppo.

The president said once Russia and Iran backed the Syrian government it was "very hard to see a way in which even a trained and committed moderate opposition could hold its ground."

Obama also insisted that he would allow Trump to "put forward his platform and his arguments," but suggested he would speak out if core U.S. values were threatened.

Obama also urged Trump to retain U.S. support for a liberal world order, warning world peace and prosperity depended 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. (rl/ez)