The United Nations said Thursday that Syria’s President Bashar al-Assad has signed a legal document confirming that his government will comply with an international ban on chemical weapons.

But the announcement came just hours after U.S. Secretary of State John Kerry rejected Assad's earlier pledge to sign the agreement and begin submitting data on his chemical weapons one month later, in keeping with the usual practice under the pact. Kerry said the usual rules cannot apply to the current situation, and he demanded speedier compliance.

U.N. Secretary General Ban Ki-moon's office said that it has received a letter from Syria's government saying Assad has signed a legislative degree providing for accession to the 1992 Convention on the Prohibition, Production, Stockpiling and Use of Chemical Weapons and on their Destruction.

The secretary general "welcomes this development" and "hopes that the current talks in Geneva will lead to speedy agreement on a way forward which will be endorsed and assisted by the international community," Ban's office said.

Hours earlier, at a news conference in Geneva after a meeting on the Syria situation with Russian Foreign Minister Sergey Lavrov, Kerry noted that Assad said a 30-day lead time after signing the agreement would be standard.

"There is nothing standard about this process," Kerry said, because Assad has used his chemical weapons. "The words of the Syrian regime in our judgment are simply not enough."

Kerry added, "Only the credible threat of force and the intervention of Putin and Russia … has brought the Syrian regime for the first time to acknowledge that it even has chemical weapons and will now relinquish them."

"Together we will test the commitment of Assad to follow through with his promises," Kerry added.

He cautioned that a U.S. military strike could occur if Assad doesn't agree to dismantle his chemical arsenal properly.

"There ought to be consequences if it doesn't take place," Kerry said.

Lavrov said the dismantling "will make unnecessary any strike against the Syrian Arab Republic."

Speaking ahead of the talks, President Barack Obama said: "I am hopeful that the discussions that Secretary Kerry has with Foreign Minister Lavrov as well as some of the other players in this can yield a concrete result, and I know that he is going to be working very hard over the next several days over the possibilities there."

Kerry and Lavrov met in Geneva on Thursday with the aim of finding a diplomatic path to avoiding outside military intervention in the Syrian civil war. A senior U.N. diplomat, speaking on condition of anonymity, told The Associated Press beforehand that the high-level meeting would be an exploratory session to guage whether they can embark on "the herculean task" of dismantling Syria's chemical weapons while the country is in conflict.

Assad earlier said in a Russian TV interview that Syria decided to cede control of its chemical weapons because of the Russian proposal and not the threat of U.S. military intervention, according to the Interfax news agency.

"Syria is placing its chemical weapons under international control because of Russia," Interfax quoted Assad as telling Russia's state-run Rossiya-24 channel. "The U.S. threats did not influence the decision."

Assad also told Rossiya-24 that Syria would submit the documents to the U.N. for the international chemical weapons agreement, the state-run Russian news agency RIA reported Thursday. Rossiya-24 did not immediately air the interview, and it was not clear when it was recorded.

On Wednesday night, Russian President Vladimir Putin increased pressure on the international community, arguing in an op-ed in the New York Times that a potential strike by the U.S. against Syria would not only claim more innocent victims but also increase violence in the Middle East and trigger a new wave of terrorism.

Russia has rejected U.S. and French demands for a binding U.N. resolution that would put Syria's chemical weapons under international control -- an idea proposed by Russia -- and that would condemn their use by Assad's forces, with "very severe consequences" for Syrian noncompliance.

Turkish Prime Minister Recep Tayyip Erdogan Thursday questioned Syria's motives for agreeing to comply with the Russian proposal that it cede control of its chemical weapons, saying Assad was buying time for new "massacres."

"The Assad regime has not lived up to any of its pledges. It has won time for new massacres and continues to do so," Erdogan said in a speech in Istanbul. "We are doubtful that the promises regarding chemical weapons will be met."

Syrian rebel leadership, for its part, rejected Russia's initiative Thursday, according to a video statement obtained by Reuters.

Representatives of the five veto-wielding members of the U.N. Security Council met late Wednesday to discuss what to include in a resolution requiring that Syria's chemical weapons stockpile be secured and dismantled. They left the session without commenting.

The Russian government is eager to avoid U.S. intervention in its ally Syria. Moscow has seized on a divided Congress and American public, which does not have much appetite for engaging in another war and accuses the Obama administration of not paying more attention to pressing domestic issues, such as the debt ceiling and immigration.

Obama's credibility has also taken a hit. He is seen by some as changing course too many times as civil war raged in Syria over the past two years, going from apparent indifference to calling for military action to discussing Russia's proposed diplomatic solution.

In a major speech Tuesday, the president asked Congress to delay a vote on military intervention -- a move that could weaken his push for punishing Assad over the alleged use of chemical weapons in an Aug. 21 attack that killed more than 1,400 people, including hundreds of children.

There is still some debate in the international community over Assad's role in the attack.

Putin, in his op-ed, appeared to pin the blame for the chemical attack on the opposition.

French Foreign Minister Laurent Fabius said Thursday that the U.N. inspectors who investigated the chemical attack would likely release their findings Monday.