By Warren Strobel and Stephanie Nebehay
GENEVA (Reuters) - U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov opened high-stakes talks on Thursday on disarming Syria's chemical weapons programs, but differences emerged at the outset over U.S. military threats against Syria.
Kerry, appearing with Lavrov at the start of what are expected to be two days of talks, said military force might be needed against Syria if diplomacy over President Bashar al-Assad's chemical weapons stockpile fails.
U.S. President Barack Obama "has made clear that should diplomacy fail, force might be necessary to deter and degrade Assad's capacity to deliver these weapons," Kerry said.
But Lavrov said U.S. threats to launch missile strikes at Syria in response to an August 21 chemical weapons attack on Damascus suburbs, which Washington says killed more than 1,400 people, should be set aside.
"We proceed from the fact that the solution of this problem will make unnecessary any strike on the Syrian Arab Republic," he said. "I am convinced that our American colleagues, as President Obama stated, are firmly convinced that we should follow peaceful way of resolution of conflict in Syria."
The Geneva talks are aimed at fleshing out Russia's proposal earlier this week that Syria agree to give up its chemical weapons stocks, believed to be among the world's largest.
Kerry and Lavrov flew here with delegations of chemical weapons and nonproliferation experts to begin to hammer out how U.N. weapons inspectors would manage the complex task of identifying, securing and neutralizing Syria's chemical weapons arsenal.
As the talks got underway, Syria on Thursday applied to join the global ban on chemical weapons, a treaty known as the Chemical Weapons Convention. Assad said in a television interview that Damascus would provide an accounting of chemical weapons stocks in 30 days, standard practice under the treaty.
Kerry questioned the offer, underscoring Washington's skepticism about Syria's promises.
"We believe there is nothing standard about this process at this moment because of the way the regime has behaved, not only the existence of these weapons - but they have been used," Kerry said.
He acknowledged the high stakes involved in these talks.
"Expectations are high. They are high for the United States, perhaps even more so for Russia, to deliver on the promise of this moment," Kerry said. "This is not a game and I said that to my friend Sergei when we talked about it initially. It has to be real. It has to be comprehensive. It has to be verifiable. It has to be credible. It has to be timely and implemented in a timely fashion, and finally there ought to be consequences if it doesn't take place."
The United States, its allies and the nonprofit Human Rights Watch say Syrian forces used sarin nerve gas against areas surrounding Damascus that had long been held by anti-Assad rebels.
Assad's government says that the rebels used the weapons. Russian President Vladimir Putin made the same claim in an op-ed in the New York Times on Wednesday.
Another key point of friction in the Geneva talks is likely to center on whether or not to use the threat of military force.
Assad said in the interview with Russian state television that he would only finalize plans to give up his arsenal if Washington dropped its threats to attack him.
A draft U.N. Security Council Resolution submitted by France this week demands that Syria declare its chemical weapons holdings within 15 days, and holds out the threat of sanctions or military force if it fails to disarm.
A senior U.S. official traveling with Kerry declined to say whether Washington endorsed the draft resolution's threat.
"All I will say is that we will talk about monitoring, verification, and enforcement," said the official, speaking on condition of anonymity.
A French diplomatic source said: "We don't think the U.S. can ultimately accept a text that is too weak because while internal (U.S.) politics may not be for a military strike, the Congress will nevertheless want a credible substitute to strikes."
Both Kerry and his Russian counterpart said they hoped to revive stalled Syria peace talks and a long-delayed peace conference known as "Geneva 2."
"We think the development of events gives additional opportunity for Geneva 2 to move ... today's situation from a stage of militaristic confrontation and to prevent any terrorist threat which is expanding in Syria and in the region," Lavrov said.
Kerry also met on Thursday with Lakhdar Brahimi, the joint U.N.-Arab League special envoy.
(Additional reporting by Tom Miles in Geneva, Louis Charbonneau at the United Nations, Tabassum Zakaria in Washington and John Irish in Paris; Editing by Sonya Hepinstall)