The United Nations Security Council has adopted a US-drafted resolution condemning the use of chlorine as a weapon in Syria and threatening measures if chemicals are used in attacks in the future.
The measure was endorsed by 14 of the 15 council members on Friday, with Venezuela abstaining in the vote.
The resolution "stresses that those individuals responsible for any use of chemicals as weapons, including chlorine or any other toxic chemical, must be held accountable".
A fact-finding mission of the Organisation for the Prohibition of Chemical Weapons (OPCW) earlier this year concluded "with a high degree of confidence" that chlorine was used on three villages in Syria in 2014, killing 13 people.
The report included eyewitness accounts of helicopters dropping barrel bombs with toxic chemicals.
OPCW did not say which side was responsible for the chlorine attacks, but addressing the Security Council, the US ambassador to the UN, Samantha Power, said there was not much doubt.
"Let's ask ourselves, who has helicopters in Syria? Certainly not the opposition. Only the regime does and we have seen them use their helicopters in countless other attacks on innocent Syrians using barrel bombs," she said.
The resolution threatens repercussions, under Chapter 7 of the UN Charter, if chemical weapons including chlorine are used again. Chapter 7 allows decisions to be enforced with economic sanctions or force.
Britain's UN Ambassador Mark Lyall Grant said the resolution "puts the Syrian regime on notice that if we receive further credible reports of use of chlorine as a weapon, then this council will take action".
Still, the Security Council would need to adopt another resolution to take any action in the event of non-compliance.
Al Jazeera's Diplomatic Editor James Bays, reporting from the UN headquarters in New York, said it was a "rare moment" when the Security Council agreed on a resolution, but stressed that it is highly unlikely that there would ever be an agreement on identifying the perpetrator.
Russia and China have vetoed previous Security Council resolutions against the Syrian government.
Vitaly Churkin, the UN ambassador of Syria's main ally, Russia, suggested that chlorine bombs went off at time when the regime's helicopters just happened to be flying in the area.
After Friday's meeting, Syrian Ambassador Bashar Jaafari lashed out at some council members for blaming his government for atrocities related to the "so-called chemical issue" and other issues.
"These people are like hyenas. The more they kill, the more they are hungry," he said.
"The Syrian government has nothing to hide."
Venezuelan Ambassador Rafael Ramirez said the council should wait until any investigation into the use of chlorine is complete before taking up the issue. The South American country, which has an antagonistic relationship with the United States, has long defended the government of Syrian President Bashar al-Assad.
Assad said in an interview with the BBC last month that his regime were "definitely not" using chlorine as a weapon.
Chlorine is not a chemical that has to be declared to the OPCW because it is also used for regular purposes in industry.
Source: Al Jazeera and agencies