President Barack Obama said on Friday the only area of U.S. understanding with Russia on Syria was on how to prevent accidental clashes between their planes engaged in the conflict, but they differed on principles and strategies to bring peace.

Speaking at a news conference after meeting with South Korean President Park Geun-hye, Obama said the Syrian civil war was a magnet for extremists and could only end with a political solution leading to a new inclusive government.

"There's no meeting of the minds in terms of strategy," he said, which reflected a fundamental difference with President Vladimir Putin over the continuing rule of President Bashar al-Assad.

"President Putin believes if he continues to do what he has been doing over the last five years, and that is to prop up the Assad regime, that the problem will be solved."

Obama said he believed in continuing the fight against the Islamic State and other extremist groups, but said the civil war "will only go away if we're able to get a political track and a legitimate inclusive government inside of Syria."

The only understanding with Russia was how to "de-conflict in the event that our planes and their planes might be occupying similar space over Syrian skies," he said. "We have arrived at an understanding and some channels for communications."

He said it was essential to get "the Iranians, the Russians, the Turks, the Gulf countries and all the interested parties to sit down and recognize we have to have a political transition if we want to end the humanitarian crisis and save the structure of a unified Syrian state."

Obama said he hoped there could be progress if talks among the parties continued and "Russia starts realizing that they are not going to be able to bomb their way to a peaceful situation inside of Syria."