BEIRUT – Investigators have rushed to Turkey to examine survivors of the chemical attack in neighboring Syria and collect samples that could reveal the nature of the toxins, the means of delivery and, ultimately, who was responsible for one of the war's most disturbing atrocities.
The victims' presence in Turkey offers a way around a problem that has bedeviled past investigations and sown confusion for policymakers: limited access to attack sites. The byproducts of the nerve agents suspected in Tuesday's attack can remain in the bloodstream long after the effects have worn off.
"Whoever wants to find out the truth and the weapon that was used has enough evidence" in Turkey, said Dr. Osama Abo Elezz, a physician from Khan Sheikhoun, the opposition-held town where the chemical attack took place. "This has not happened before."
But even with the heightened media attention and the anguish the attack has provoked in the highest offices in the U.S. and other Western capitals, the inspectors have been hamstrung by a thicket of rules and precautions that could frustrate even the most determined investigators.
Witnesses described pandemonium at the Bab al-Hawa border crossing, where medical staff, terrified of exposure to toxins, donned hulking hazmat suits and pushed victims on gurneys to a decontamination tent. Even second-hand exposure to sarin, the nerve agent suspected in the attack, can produce symptoms leading to death.
In the past, Turkish authorities have not always facilitated weapons probes, according to two doctors who cross regularly from Turkey into Syria to treat patients.
"Turkey's hesitation is nothing new. Turkey has never wanted to be involved in the operations," said Dr. Hossam Nahas, the lead coordinator for the chemical weapons response team of the Union of Medical Care and Relief Organizations, a network of Syrian doctors that provides support to medical staff in rebel-held areas.
Another physician, Dr. Zaher Sahloul, who is Syrian American, said he has detected little appetite among Turkish officials to investigate allegations of war crimes they were powerless to stop.
"If they think a sample is coming, they will block it," Sahloul told The Associated Press in the wake of reports last week that patients in the central Syrian town of Latamneh were arriving at hospitals with muscle spasms and foaming at the mouth — signs that a nerve agent might have been dispersed in a presumed government or Russian airstrike in the area.
That suspected attack was five days before the more dramatic assault Tuesday in Khan Sheikhoun. The quick global response to the latest attack, as well as the rush of victims to the Turkish border may have compelled Turkish authorities to open the border and offer greater cooperation, Sahloul said Thursday.
"There are several reasons for the change in response. The first is the scale of the attack and the fact that many victims are children and women. And the public outrage, globally," Sahloul told the AP by phone from the Chicago hospital where he works. "All of these factors have been changing the level of seriousness they take in these attacks."
In February, Russia and China vetoed a U.N. Security Council resolution authorizing punitive actions against the Syrian government after a joint investigative team from the United Nations and the Organization for the Prohibition of Chemical Weapons watchdog group concluded that the government carried out chlorine gas attacks three times in 2014 and 2015.
The OPCW, which has the international authority to investigate such incidents, said Thursday it was "already collecting and analyzing information" about Tuesday's attack, and had initiated contact with the Syrian authorities.
Residents, however, said they have yet to see any international observers arriving in Khan Sheikhoun. Video from the town, distributed Thursday by the activist-run Syrian Institute For Justice, showed residents wearing gloves and dust masks collecting samples from the crater where it was believed the missile carrying the toxins struck.
Nahas said it was crucial that inspectors be allowed into the attack site to counter claims by the Russian and Syrian governments the chemicals were released when a Syrian airstrike struck a rebel munitions and chemical factory.
Syrian Foreign Minister Walid Moallem said the Syrian government might authorize an investigative team to enter the town on the condition it travels from Damascus, not Turkey. He said Syria would also need assurances any investigation would be impartial and non-politicized.
The Turkish Health Ministry, meanwhile, said Thursday its own examinations of victims "suggest that the patients were exposed to ... sarin." It said it would allow the OPCW to take samples for its own investigation to The Hague, Netherlands.
The international chemical weapons watchdog sets the gold standard for chemical weapons investigations, but for many Syria observers, its work is frustratingly slow.
"I appreciate the international community have wanted to wait for the full due process and the full chain of evidence," said Hamish de Bretton-Gordon, a former British army chemical weapons expert and director of Doctors Under Fire. "But that takes years, and we're not four years down the line from chemical weapons usage and it is now the norm."
To de Bretton-Gordon, as well as intelligence officials and political leaders in the West, it is already clear from video of the aftermath of Tuesday's attack that the victims were exposed to sarin gas.
"I'm absolutely convinced," Bretton-Gordon said. "For those who don't die immediately, it's the convulsions and pinpoint pupils. Because nerve agents basically attack your nerves and stop them working, which is why your eyes don't work. ... Because the nerve in the eye is dead."
Moreover, the government claim that it struck a rebel warehouse storing toxic gas does not hold water, he said. Sarin is not stable enough to withstand the intense heat or pressure of a bomb blast.
"That is how you destroy sarin — you burn it or you blow it up," he said.
Also, if patients were exposed to sarin from a warehouse explosion, he said, they would have shrapnel wounds, as well as symptoms of nerve poisoning.
Associated Press writers Sarah El Deeb in Beirut, Michael Corder in Amsterdam and Jill Lawless in London contributed to this report.