After authorizing U.S. weapons for rebels in Syria, President Barack Obama faces difficult talks on ending the civil war there when he meets next week with the Syrian government's most powerful ally: Russian President Vladimir Putin.
The pair will hold their first private, face-to-face meeting in a year on Monday at the G8 conference in Northern Ireland.
Obama will focus on finding common ground with Putin on talks toward a political settlement in Syria, said Ben Rhodes, the White House deputy national security adviser. "There are no illusions that that's going to be easy," he said.
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Obama will discuss U.S. evidence that Syrian President Bashar al-Assad's forces have used chemical weapons - crossing what the American president has called a "red line" in the 2-year-old civil war, the White House said.
Syria is Russia's only ally in the Middle East and Moscow has frustrated the United States by its diplomatic support for Assad and its threats to send S-300 anti-aircraft missiles that could prevent the establishment of a Western no-fly zone in Syria.
Working to overcome mistrust between them, Moscow and Washington are trying to set up a Syrian peace conference in Geneva next month.
But the chances of it taking place have begun to fade as Syria's conflict descends into a messy proxy war pitching Assad backed by Russia, Iran and Lebanese Hezbollah militants against the mostly Sunni rebels supported by the United States, Turkey, Qatar, Saudi Arabia, Britain and France.
Russian Foreign Minister Sergei Lavrov has told Secretary of State John Kerry that U.S. accusations of chemical weapons use by Assad's forces "are not backed up by verified facts," the Russian foreign ministry said on Friday.
Lavrov also warned that U.S. military support for Syrian rebels could escalate violence, it said.
Even some U.S. officials are worried that Obama’s reluctant decision to provide limited amounts of small arms and ammunition to the Syrian opposition is enough to drag the U.S. into a third Mideast war but not enough to win it.
“Arming the Syrian rebels is unlikely to tip the balance in their favor,” said Shadi Hamid, director of research at the Brookings Institution’s Doha Center. “It might have made a difference a year ago, but, today, the Assad regime -- particularly after re-taking Qusair -- has the advantage.”
The first shipment of small arms from the United States to Syrian rebels is weeks away and already, Syrian opposition says it will need heavier weapons if it is thwart al-Assad's expected offensive to retake Aleppo, the nation’s largest city and commercial capital.
Speaking a day after Washington said it would arm the rebels, the Free Syrian Army commander told Reuters his forces urgently needed heavier weapons in Aleppo to thwart the Assad government's expected massive assault.
"If we have done the training ... and have enough weapons and ammunition I think it will be a matter of time, about six months, maybe less, maybe more, to collapse the regime."
Senator Bob Casey, a Pennsylvania Democrat who spoke with Idris by phone this week, said of the opposition leader, “He was very clear: Machine guns and RPGs can’t compete with air power. He asked specifically in addition to conventional arms for anti-tank weapons that could deal with the Russian tanks and also anti-aircraft weapons.”
Idris alsos is urging the United States to impose a no-fly zone over Syria, another hot button for the Putin administration.
"They use modern jets to bombard the cities and towns, and civilians and fighters, and we don't have any effective kind of weapons for air defence," Idris told Reuters on Saturday
Lavrov said on Saturday any attempt to enforce a no-fly zone over Syria using F-16 fighter jets and Patriot missiles from Jordan would violate international law.
"There have been leaks from Western media regarding the serious consideration to create a no-fly zone over Syria through the deployment of Patriot anti-aircraft missiles and F-16 jets in Jordan," said Lavrov, speaking at a joint news conference with his Italian counterpart.
"You don't have to be a great expert to understand that this will violate international law," he said.
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Imposing a no-fly zone could require the United States to destroy Syria's sophisticated Russian-built air defenses.Washington says it has not excluded a no fly zone but is also considering other options.
"We have been clear that we are not excluding options but at this stage no decision has been taken," said Susan Rice, the U.S. ambassador to the United Nations and Obama's incoming national security adviser.
Obama's authorization of U.S. weapons to Syrian rebels is likely to upset Putin, whose rhetoric has become more anti-American since he returned to Russia's presidency last year.
In a series of comments on Tuesday that ranged from criticism of America's dropping of the atomic bomb in 1945 to its treatment of Native and African Americans, Putin accused Washington of supporting pro-democracy protests that have seen thousands take to Moscow's streets.
Russia has been particularly exasperated with U.S. Ambassador Michael McFaul, who has built deeply close links with dissident groups. It has complained repeatedly about foreign and particularly U.S. funding of activist groups and kicked out the U.S. Agency for International Development.
"Our diplomatic service does not cooperate actively with Occupy Wall Street but their diplomatic service interact actively with (Russian opposition figures) and directly supports them," Putin told English-language state channel RT.
In an apparent move to irritate Washington further, Putin said Russia might be willing to consider a plea for asylum from Edward Snowden, who leaked surveillance secrets from the U.S. National Security Agency.
Russia under Putin has become more militarily assertive than at any time since the end of the Cold War, sometimes with direct implications for U.S. Syria policy.
Last year, Moscow sent a flagship aircraft carrier to loiter off the Syrian coast to deter any foreign action. It said it will restore its permanent naval presence in the Mediterranean.
"What we're seeing here is another sign of a move to a much more multipolar world," said Nikolas Gvosdev, professor of national security studies at the United States Naval War College. "It's about countries like Russia putting certain states such as Syria off-limits for U.S. intervention. If you're going to get things done in the modern world, you're going to have to get great powers to work together."
Information from Reuters, AFP, The Associated Press and Bloomberg were used in this report.
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