mage from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, shows a building at the Syrian government checkpoint on fire, in Dael, Syria. | Ugarit News via AP video/AP

By Matthew Schofield McClatchy Newspapers

WASHINGTON — Chemical weapons experts voiced skepticism Friday about U.S. claims that the government of Syrian President Bashar Assad had used the nerve agent sarin against rebels on at least four occasions this spring, saying that while the use of such a weapon is always possible, they’ve yet to see the telltale signs of a sarin gas attack, despite months of scrutiny.

“It’s not unlike Sherlock Holmes and the dog that didn’t bark,” said Jean Pascal Zanders, a leading expert on chemical weapons who until recently was a senior research fellow at the European Union’s Institute for Security Studies. “It’s not just that we can’t prove a sarin attack, it’s that we’re not seeing what we would expect to see from a sarin attack.”

Foremost among those missing items, Zanders said, are cellphone photos and videos of the attacks or the immediate aftermath.

“In a world where even the secret execution of Saddam Hussein was taped by someone, it doesn’t make sense that we don’t see videos, that we don’t see photos, showing bodies of the dead, and the reddened faces and the bluish extremities of the affected,” he said.

Other experts said that while they were willing to give the U.S. intelligence community the benefit of the doubt, the Obama administration has yet to offer details of what evidence it has and how it obtained it.

White House foreign policy adviser Benjamin Rhodes gave dates and places for the alleged attacks – March 19 in the Aleppo suburb of Khan al-Assal; April 13 in the Aleppo neighborhood of Shaykh Maqsud; May 14 in Qasr Abu Samrah in Homs province, and May 23 in Adra, east of Damascus. But he provided no details of the fighting that was taking place or the number of dead in each incident. He said the United States estimated that 100 to 150 had died in all.

“Ultimately, without more information, we are left with the need to trust the integrity of the U.S. intelligence community in arriving at its ‘high confidence’ judgment,” Greg Thielmann, a senior fellow at the Washington-based Arms Control Association, said in an email. While he said that “my guess is they have it right,” he also noted that the White House statement was “carefully and prudentially worded” and acknowledged the lack of a “continuous chain of custody for the physiological samples from those exposed to sarin.”

“It does not eliminate all doubt in my mind,” he said.

Philip Coyle, a senior scientist at the Center for Arms Control and Non-Proliferation in Washington, said that without hard, public evidence, it’s difficult for experts to assess the validity of the administration’s statement. He added that from what is known, what happened doesn’t look like a series of sarin attacks to him.

“Without blood samples, it’s hard to know,” he said. “But I admit I hope there isn’t a blood sample, because I’m still hopeful that sarin has not been used.”

Even a proponent of the United States providing military assistance to the rebels raised doubts about the possible motive for announcing the chemical weapons conclusion….more here