A senior Obama administration official said Friday that the United States was encouraged by the initial inventory that the Syrian government had submitted of its chemical weapons arsenal.
"We were pleasantly surprised by the completeness of their declaration," said the official, who declined to be identified because he was not authorized to speak publicly on the matter.
"It was better than expected," he added.
The Organization for the Prohibition of Chemical Weapons, the watchdog group known as the O.P.C.W. that oversees the international agreement banning poison gas, said on Friday that Syria had provided "an initial declaration" of its chemical weapons program.
The submission met the first deadline for Syrian compliance that was set down by the framework agreement that the United States and Russia concluded in Geneva last weekend.
American, British, Chinese, French and Russian diplomats are debating the terms of a United Nations Security Council resolution that would enforce the agreement. Secretary of State John Kerry said on Thursday that it was essential for the Council to adopt the resolution next week.
"It started coming in yesterday," Michael Luhan, a spokesman for the O.P.C.W., said of the Syrian declaration. Mr. Luhan, who spoke in a telephone interview from The Hague, said that the organization's technical experts were studying the declaration but would not give additional details.
The declaration's completeness is an early test of President Bashar al-Assad's commitment to relinquish Syria's chemical weapons arsenal.
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The United States and Russia agreed in Geneva that Syria has about 1,000 tons of precursor chemicals and chemical agents, including sulfur mustard and sarin gas.
The fact that Russia, which has been one of the principal supporters of the Assad government, reached a consensus with the United States on the size of the arsenal after receiving an intelligence briefing by American experts suggested that the Syrian government would eventually declare a similar figure.
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Still, American officials had been waiting to see if the Syrian declaration would be submitted within a week of the framework agreement, as the accord requires, and whether it would be comprehensive.
Under the framework agreement, the declaration is to detail types and quantities of all its chemical agents, munitions and precursor chemicals as well as all laboratories for developing the agents and facilities for producing weapons.
Marie Harf, the deputy State Department spokeswoman, would not characterize the Syrian declaration, saying only that the United States will make "a careful and thorough review of the initial document."
The O.P.C.W. does not publicly disclose the contents of declarations. But its assessment of the accuracy and thoroughness of Syria's statement will be crucial in determining how inspectors can best proceed with the agreement's next stage, which includes far more formidable tests of the Assad government's cooperation.
By November, international monitors are to inspect all of Syria's declared sites, and equipment to produce and mix chemical weapons is to be destroyed.
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Syria's entire arsenal is to be eliminated by the middle of 2014, although Mr. Assad has said that process could take a year.
Under the framework agreement, the United States and Russia are to outline procedures for quickly eliminating Syria's chemical weapons program and verifying that the country is not hiding any weapons or stocks.
An American and Russian draft outlining those procedures is subject to endorsement by the O.P.C.W. executive council, followed by codification in the Security Council resolution mandating elimination of Syria's chemical arsenal.
The executive council was to have met this weekend, but instead will likely convene toward the middle or end of next week, said Mr. Luhan, who gave no reason for the delay.
The United States has identified at least 45 sites associated with Syria's chemical weapons program and has suggested that half of them had "exploitable" quantities of chemical warfare materials, though American officials said Syrian forces had been moving stocks, so the locations could have changed.
American officials said the sites where Syria's chemical weapons and stocks are held are controlled by Mr. Assad's government. While Russia has agreed with the estimate of the size of Syria's arsenal, it has not endorsed the American list of the sites linked to the Syrian program.
—By Michael Gordon and Nick Cumming-Bruce, The New York Times