PARIS (Reuters) - U.S. President Barack Obama urged Turkey on Tuesday to reduce tensions with Moscow after the downing of a Russian warplane and to seal its border with Syria to choke off the supply of money and fighters to Islamic State militants.
He also raised the specter of Afghanistan in warning Russia against getting bogged down in its military campaign to prop up Syrian President Bashar al-Assad.
But hopes of the de-escalation called for by Obama suffered a setback when Russia officially announced a list of sanctions to be imposed on Turkey and sources said Moscow may also freeze work on a major gas pipeline project.
Obama met Turkish President Tayyip Erdogan in Paris, where they have been attending a climate summit, a week after Turkish jets shot down a Russian warplane along the Syrian border.
Obama stressed that U.S. support for its NATO ally's security remained steadfast.
"The United States supports Turkey's right to defend itself and its airspace and its territory," Obama said. "We discussed how Turkey and Russia can work together to de-escalate tensions and find a diplomatic path to resolve this issue."
Obama told Erdogan that the Islamic State militant group, also known as ISIL, must be pursued by all sides, echoing a message he delivered to Russian President Vladimir Putin on Monday. "We all have a common enemy, and that is ISIL, and I want to make sure that we focus on that threat," Obama said.
Tensions between Russia and Turkey have complicated U.S. efforts to prod Moscow into steering its military might towards Islamic State rather than Western-backed Syrian opposition groups. Putin supports Assad, while Obama and Erdogan want him to go.
Obama said he did not expect a quick reversal of Putin's strategy in Syria, but Moscow may eventually align itself with the U.S.-led coalition fighting Islamic State.
"I think Mr. Putin understands that with Afghanistan fresh in the memory for him to simply get bogged down in an inconclusive and paralyzing civil conflict is not the outcome that he's looking for," Obama told a news conference.
The Soviet Union invaded Afghanistan in 1979 to prop up a pro-Moscow government but withdrew a decade later after failing to beat Afghan guerrillas.
With Putin committed to keeping Assad in power in Damascus, Obama did not expect Russian warplanes to shift their focus soon to hitting Islamic State rather than other opposition groups. "I don't expect that you're going to see a 180 turn on their strategy over the next several weeks," Obama said.
Turkish Prime Minister Ahmet Davutoglu called for the opening of communication channels between Ankara and Moscow to prevent further incidents like the downing of the warplane.
Putin has said Turkey shot down the jet to protect supplies of oil from Islamic State, a claim that Erdogan dismisses as "slander".
Obama said Turkey had made some progress in sealing its border with Syria but Islamic State was still exploiting gaps to bring in foreign fighters and sell oil.
"We've got to choke them off. We have to choke off how they make money. We've got to choke off their ability to bring in new fighters because, you know, we've taken tens of thousands of their fighters off the battlefield," Obama said.
Russia on Tuesday approved sanctions to be imposed on Turkey for shooting down the plane. The official list included fruit and vegetables such as tomatoes, onions, grapes and apples, as well as chicken products.
Moscow may also suspend work on the Turkish Stream gas pipeline project, two sources in Russian gas giant Gazprom told Reuters.
While both Erdogan and Davutoglu have said they do not want an escalation in tensions with Russia, they have also indicated they have no intention of issuing an apology for the downing of the jet, as Moscow has demanded.
Both Putin and Erdogan are strong-willed leaders ill-disposed to being challenged and playing to domestic audiences who like their pugnacity. Neither wants to be seen to back down first. "Putin and Erdogan are two peas in a pod. They're very similar characters," said one top European diplomat.
Erdogan said following the meeting with Obama that tension with Russia was harming both countries.
"The tensions in the region sadden us. It is causing harm to both sides," he said. "Our concern is to not come out badly from this, but on the contrary to turn this into peace and contribute to the peace in the region," Erdogan said.
Obama said the United States was eager to accelerate work on its military-to-military relationship with Turkey to ensure its NATO ally was safe and to help resolve the conflict in Syria.
In Moscow, Kremlin spokesman Dmitry Peskov said similar ties between Russia and Turkey had failed. "Military channels existed and were meant to not allow such tragedies. These channels didn’t work and not through the fault of the Russian side," he said.
Additional reporting by Daren Butler in Istanbul, Darya Korsunskaya in Moscow, Noah Barkin in Berlin, Roberta Rampton and Doina Chiacu in Washington; Editing by James Regan and Giles Elgood