U.S. President Barack Obama said on Wednesday that Russia had to shift its focus from propping up Syrian President Bashar al-Assad and concentrate on the war against Islamic State.
US president calls on Russia to focus on war against IS in Syria
"That's not how they've been operating over the last several weeks. It may be that now having seen ISIL take down one of their airliners in a horrific accident, that reorientation continues."
Speaking just hours after President Vladimir Putin vowed to hunt down those responsible for blowing up a Russian airliner and intensified air strikes against militants in Syria, Obama said it was a fitting response.
"If in fact he shifts his focus and the focus of his military to what is the principal threat - and that is ISIL (Islamic State) - that is something that we very much want to see," Obama said on the sidelines of the Asia-Pacific Economic Cooperation (APEC) summit in Manila.
Obama said he had held repeated discussions with Putin last weekend at the G20 summit in Turkey and earlier at the United Nations in New York. More talks would be held with Moscow, he said.
He added: "The problem has been that their initial military incursion into Syria may have been more focused on propping up Mr Assad and targeting the moderate opposition as opposed to targeting those folks who threaten us, Europe and Russia as well."
Russia began air strikes in Syria at the end of September. It has always said its main target is Islamic State, but most of its bombs in the past hit territory held by other groups opposed to its ally Assad.
A senior French government source said Russia had launched air strikes against the Islamic State stronghold of Raqqa in northern Syria on Tuesday, signalling Moscow was becoming more concerned about the threat posed by Islamic State.
Putin ordered the strikes after an official investigation concluded that an Airbus A321 that crashed over Egypt last month was brought down by a bomb.
The Metrojet plane had been returning Russian holidaymakers from the Sharm al-Sheikh resort to St Petersburg when it broke up over the Sinai Peninsula, killing all 224 on board.
A group affiliated with Islamic State claimed responsibility.
Also speaking in Manila, Russian Prime Minister Dmitry Medvedev said his country could beat terrorism on its own but the best option would be for Moscow and the West to put aside their differences and fight together.
However, he added the West's attitude towards Russia looked "weird" in light of last week's militant attacks in Paris and the downing of the Russian airliner.
The United States and its allies have been at odds with Russia both over the future of Assad in Syria and the conflict in Ukraine.
"An act of terror with our plane and the terror attack in Paris ... have sharpened the global political agenda," Medvedev said.
"The war is declared against the whole civilised world. The threat is global and, alas, is real. So the stance of some Western countries on Russia looks weird," Medvedev said, adding the West's stance towards Moscow was short-sighted.
"I do believe we should be together in this fight."
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