Global chemical weapons inspectors will visit the last two unverified Syrian chemical weapons sites as soon as security conditions allow in the midst of an ongoing civil war, a UN official said Tuesday.

Sigrid Kaag, the head of the joint mission of the United Nations and the Organization for the Prohibition of Chemical Weapons, told the Security Council that the inspectors will check the last two sites as soon as possible. The inspectors last week said they had visited 21 of 23 sites declared by Damascus. "The intent is to visit them in future, subject to security conditions in the country," she said.

The OPCW said last week that Syria had met the Nov. 1 deadline to destroy or "render inoperable" all chemical weapon production facilities and machinery for mixing chemicals into poison gas and filling munitions.

Kaag cited the "constructive co-operation of the Syrian authorities" in helping catalogue and open for inspection its chemical weapons sites.

Syria is believed to possess around 1,000 metric tons of chemical weapons, including mustard gas and sarin. Damascus already had given preliminary details to the OPCW when it declared it was joining the organization in September.

The move warded off possible U.S. military strikes in the aftermath of an Aug. 21 chemical weapon attack on a Damascus suburb. Washington and U.S. allies accuse the Syrian government of being responsible for the attack, while Damascus blames rebels.

"Our credible threat to use force proved a catalyst in focusing the international community on a diplomatic solution," U.S. Ambassador Samantha Power said.

"We have made significant progress in taking away a potent weapon of war and terror from (Syrian President Bashar) Assad and his forces," Power said. "This deal takes away a weapon that Assad and his forces have used for tactical military advantage. This is not something he wanted, and it is not something that heals him."

But, she added, "Eliminating Syria's chemical weapons is not a substitute for ending he violence engulfing the country."

OPCW inspectors were hastily dispatched to Syria in October and have begun overseeing destruction work to ensure that machines used to mix chemicals and fill munitions with poisons are no longer functioning.

It has not yet been decided how or where destruction of Syria's chemical weapons will happen. Damascus' declaration includes a general plan for destruction that will be considered by the Organization for the Prohibition of Chemical Weapons' 41-nation executive council on Nov. 15.

At The Hague, the OPCW's director-general, Ahmet Uzumcu, told executive council members Tuesday that Syria wants its poison gas and nerve agent stockpile destroyed outside the country.

Uzumcu told the OPCW's executive council that Syria's proposal that chemical weapons be destroyed in another country, "remains the most viable option." It is not yet clear where outside Syria the destruction could happen. Norway has turned down a request to have the material destroyed on its territory.

At the United Nations, Russian Ambassador Vitaly Churkin said "Russia is not going to do the actual destruction of chemical weapons, but Russian participation is quite possible."

He said Syria cites "practical challenges" of destroying chemical weapons amid its civil war and "resource limitations" as reasons for shifting the destruction outside the country.

The OPCW's executive council has until Nov. 15 to approve Syria's plan as part of a tight timeline that calls for the total destruction of the country's chemical weapons program and stockpiles by mid-2014. Officials from Syria are visiting the OPCW this week to try to finalize the destruction plan.