BEIRUT -- The deadly nerve agent sarin was used in an attack that killed scores of civilians in northern Syria this month, the global chemical-weapons watchdog said Wednesday.
The attack, which President Donald Trump's administration has attributed to the Syrian government, elicited horror across Western capitals and prompted the United States to launch its first military action against Syrian President Bashar Assad, six years into the country's civil war. The fighting has killed an estimated 400,000 people and displaced half of Syria's population.
The Organization for the Prohibition of Chemical Weapons said Wednesday that samples from 10 victims of the attack indicated exposure to sarin or a sarinlike substance.
"While further details of the laboratory analyses will follow, the analytical results already obtained are incontrovertible," said Ahmet Uzumcu, the organization's director-general.
The attack in the northwestern town of Khan Sheikhoun woke hundreds of civilians in the early hours of April 4. Within minutes, many were choking and in convulsions on the ground. Others had died in their sleep.
At least 90 people were killed and more than 500 others affected, according to monitoring groups and doctors.
International conventions prohibit the use of sarin, which turns victims' nervous systems against them and can kill within seconds. On April 4, survivors said they felt as if their lungs were on fire.
Assad's government denies using chemical weapons against its own people, despite its involvement in a 2013 sarin attack that is believed to have killed more than 1,000 residents of the rebel-held Damascus suburbs.
On Wednesday, France said it would soon provide proof of the Syrian regime's involvement in the latest attack, as well.
"There is an investigation underway [by] the French intelligence services and military intelligence ... it's a question of days and we will provide proof that the regime carried out these strikes," said French Foreign Minister Jean-Marc Ayrault.
"We have elements that will enable us to show that the regime knowingly used chemical weapons," he added.
Also on Wednesday, Israeli defense officials said Assad still has up to 3 tons of chemical weapons.
A senior military official told reporters that the Israeli intelligence estimates that Assad has "between 1 and 3 tons" of chemical weapons.
The assessment was confirmed by two other defense officials. All officials spoke on condition of anonymity under military briefing rules.
Assad agreed in 2013 to declare and dispose of all his chemical weapons under U.N. supervision to avert U.S. strikes after the Damascus attack, but his forces have repeatedly been accused of using them since then.
The disarmament, which was carried out during a chaotic conflict, always has been the subject of some doubt, and there is evidence that the Islamic State group and other insurgents have acquired chemical weapons.
Ahead of disarmament, Assad's government disclosed it had some 1,300 tons of chemical weapons, including sarin, VX nerve agent and mustard gas.
The entire stockpile was said to have been dismantled and shipped out under international supervision in 2014 and destroyed. The chemical weapons were shipped outside Syria and destroyed abroad, with the most toxic material disposed of at sea aboard a U.S. ship. But doubts began to emerge soon afterward that not all such armaments or production facilities were declared and destroyed.
Earlier this week, Assad's former chemical-weapons research chief told Britain's The Telegraph that Syria had "at least 2,000 tons" of chemical weapons before the war and declared only 1,300.
Former Brig. Gen. Zaher al-Sakat said the Syrian government still possessed hundreds of tons of chemical weapons.
In Syria, the evacuation of thousands of Syrians from four besieged areas resumed Wednesday, state media outlets and activists said, days after a bombing killed more than 120 evacuees and delayed the widely criticized population transfer.
The Central Military Media said 3,000 residents of two pro-government villages, Foua and Kfarya, left Wednesday in 45 buses bound for government-controlled Aleppo. Another 11 buses carrying some 500 people, including opposition fighters, left Madaya and Zabadani, near Damascus, heading toward the northern rebel-held Idlib province.
The opposition-run Syrian Observatory for Human Rights also reported the transfer, which it says includes 800 armed men from both sides. Some 160, mostly gunmen, had remained in Zabadani.
Information for this article was contributed by Louisa Loveluck of The Washington Post and by Josef Federman and staff members of The Associated Press.
A Section on 04/20/2017