U.S. Secretary of State Hillary Rodham Clinton's accusation that Russia "dramatically" escalated the crisis in Syria lost steam Thursday when the State Department acknowledged that the helicopters she accused Moscow of sending were actually refurbished ones already owned by the Assad regime.

The claim had complicated the Obama administration's larger goals for Syria and U.S.-Russia relations before a key meeting of the nations' two leaders.

'Whether they are new or they are refurbished, the concern remains that they will be used for the exact same purpose that the current helicopters in Syria are being used, and that is to kill civilians.'— Victoria Nuland, State Department spokeswoman

In answering a question at the Brookings Institution on Tuesday, Clinton omitted the detail that the helicopters were not new when she said the U.S. was "concerned about the latest information we have that there are attack helicopters on the way from Russia to Syria."

State Department spokeswoman Victoria Nuland insisted that the nuance meant little, even as she refused to explain why the department didn't divulge the information earlier.

"Whether they are new or they are refurbished, the concern remains that they will be used for the exact same purpose that the current helicopters in Syria are being used, and that is to kill civilians," Nuland told reporters. "These are helicopters that have been out of the fight for some six months or longer. They are freshly refurbished. The question is simply what one expects them to be used for when one sees what the current fleet is doing.

"When you look at the Soviet- and Russian-made helicopters that are in use in Syria today, every helicopter that is flying and working is attacking a new civilian location," she added. "So the concern is when you add three more freshly refurbished helicopters to the fight, that is three more that can be used to kill civilians."

Clinton's accusation prompted a stern Russian denial and countercharges of hypocrisy against the U.S. for selling military equipment, including jet engines and harbour patrol boats, to Bahrain despite that Arab country's civil strife. And the secretary of state's tough talk and evident frustration even took some in the Obama administration by surprise, with the White House opting for softer language in the following days to outline U.S. concerns about Russia's role.

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U.S. Secretary of State Hillary Rodham Clinton speaks at the State Department in Washington Tuesday. Clinton's charge that Russia is sending attack helicopters to Syria escalated the war of words between the former Cold War foes, but on Thursday the State Department clarified her statements. (Pablo Martinez Monsivais/Associated Press)

"The fact that we have disagreements with Russia on some matters, Syria being one of them right now, does not mean that we cannot move forward with the Russians on areas where we agree or areas where we see more eye to eye," White House press secretary Jay Carney said Thursday, noting that there was "nothing new" in the intelligence report that Clinton based her charge on.

He brushed aside questions about whether the U.S. might yank support for Russia's membership in the World Trade Organization if Russia refuses to help on Syria.

The United States fears Syria is sliding into a violent sectarian free-for-all and that if there is any window left to negotiate a deal with President Bashar Assad, it is slamming shut. Russia is seen as a key go-between, although its influence over Assad is far from total. And up to now, Moscow has shown little willingness to help in the U.S.-led effort on a political transition plan that would end the Assad family's four-decade dictatorship.

With opposition groups estimating that 13,000 people have died, the impasse over Syria will likely be a main topic of a meeting next week between U.S. President Barack Obama and Russian President Vladimir Putin. It is the two leaders' first face-to-face since Putin's return to the presidency last month, and the Russian leader is likely to use the session to set out complaints about U.S. foreign policy in several areas.

Clinton's charge over the helicopters could become an afterthought as the U.S., Russia and other nations engage in tough diplomacy to somehow pacify Syria after more than a year of brutal government crackdowns on peaceful dissenters and the emergence of an increasingly fierce armed insurgency. But it has already taken away attention from transition strategies at precisely the time the U.S. had hoped to broaden international efforts to include Russia and China, key veto-wielding members of the UN Security Council who have twice prevented the global body from adopting binding sanctions against Assad's government.

Part of the White House's caution reflects pragmatism in a relationship that is seen as key for blunting threats around the world. Russia's powerful stature in numerous world bodies and traditional counterweight to the U.S. in the Security Council give it leverage and power beyond its economic or military power. It is seen as a linchpin in the international campaign to deny Iran a nuclear weapon and ensure a smooth shutdown of the Afghanistan war.

'The fact that we have disagreements with Russia on some matters, Syria being one of them right now, does not mean that we cannot move forward with the Russians on areas where we agree or areas where we see more eye to eye.'—Jay Carney, White House press secretary

Obama may have political reasons, too, for wanting to avoid a public spat with Russia during an election year after setting a better relationship with America's Cold War foe as a main foreign policy directive of his first term. The so-called reset has had limited success, with the U.S. and Russia butting heads on everything from missile defence to treatment of Russian opposition political groups.

On Syria, the administration is hoping to persuade Russia to change its position.

The Russians have refused to entertain any talk of a Libya-style military intervention in Syria, its closest ally in the Arab world and the host of its only naval base in the Mediterranean Sea. It has also put a far greater emphasis on criticizing armed Syrian rebels for their attacks, with language that has appeared to equate their violence to that of the Assad regime. But Moscow hasn't ruled out a negotiated exit for the 46-year-old Assad, who assumed power when his father died in 2000.

On Thursday, the State Department's No. 2, William Burns, met with Russian Foreign Minister Sergey Lavrov in Afghanistan. The talks were constructive but differences remained, Nuland told reporters in Washington.