Updated

The United States has circulated a draft resolution in the U.N. Security Council that condemns the use of toxic chemicals such as chlorine in Syria without assigning blame, while threatening militarily enforced action in the case of further violations.

The draft obtained Thursday by The Associated Press follows last month's condemnation by the world's chemical weapons watchdog of the use of chlorine in Syria as a breach of international law.

While its fact-finding mission concluded "with a high degree of confidence" that chlorine was used on three villages in Syria last year, killing 13 people, the executive council of the Organization for the Prohibition of Chemical Weapons did not assign blame.

Some council members such as Britain have blamed Syria's government for the attacks, pointing out that OPCW reports have linked chlorine attacks to helicopters and that only Syria's government has helicopters.

The new draft threatens action against further violations under a council resolution in 2013 that banned Syria's use of chemical weapons. The resolution also applies to any party in the Syrian conflict, which is about to enter its fifth year and has killed an estimated 220,000 people.

The draft says such actions should be imposed under Chapter 7 of the U.N. Charter, meaning they could be militarily enforced.

Syria joined the OPCW in 2013 and declared a 1,300-ton chemical weapon arsenal that has since been destroyed, though some council members worry that the government didn't declare everything it had. Chlorine is not a chemical that has to be declared to the OPCW because it is also used for regular purposes in industry.

The fact-finding mission's report on last year's attacks said 32 of 37 people interviewed "saw or heard the sound of a helicopter over the village at the time of the attack with barrel bombs containing toxic chemicals."

Syria denies using chlorine or other chemical weapons and blames "terrorists" for such attacks.

The country's move to join the OPCW came amid international outcry and the threat of U.S. airstrikes over a chemical attack on a Damascus suburb that killed hundreds of civilians. The U.S. and Western allies accused the Syrian government of being responsible for that attack, while Damascus blamed rebels.

The 2013 resolution was a rare agreement on Syria by the council, which has been blocked from taking other actions by the threat of a veto from Russia, Syria's ally. An attempt to refer the situation in Syria to the International Criminal Court last year, for example, failed.