Children carry portraits of Bashar al-Assad during a celebration of the capture of Qusayr by Syrian pro-government forces on June 6, 2013. Photo: MAHMOUD ZAYYAT/AFP/Getty Images

In his interview with Charlie Rose this week, President Obama emphasized that Syria is not Iraq, but there’s at least one similar theme emerging. While the White House announced last week that the U.S. intelligence community has “high confidence” that the Assad regime used chemical weapons, thus changing Obama’s “calculus” on arming the rebels, some experts say they’re still skeptical. The U.S., Britain, and France claim they have evidence that Syrian troops used sarin gas on the battlefield, but it’s unclear how the data was obtained or analyzed. “There are so many people who would like us to believe that the regime used chemical weapons,” a former senior U.S. official who has investigated weapons of mass destruction told the Washington Post. “You have to question whether any of those advocates were involved in collecting the evidence.”

The United Nations will only make a judgment based on evidence collected by its own inspectors, and while the chief U.N. weapons inspector is headed to the region next week to interview witnesses in neighboring countries, it’s increasingly unlikely that Assad will allow U.N. inspectors into Syria itself. The U.S., Britain, and France have been calling for a U.N. investigation for months, and in the meantime they’ve each concluded that chemical weapons were used.

The countries based their assessments on evidence such as blood, tissue, and soil samples smuggled out of Syria by rebels or intelligence agents, but officials said they couldn’t be more specific without compromising ongoing operations. “You can try your best to control the analysis, but analysis at a distance is always uncertain,” said David Kay, a former U.N. weapons inspector who led the search for weapons of mass destruction in Iraq after the 2003 invasion. “You’d be an idiot if you didn’t approach this thing with a bit of caution.” One senior diplomat countered that the evidence is convincing because it was collected from many different sources, some of them non-Syrian.

The fact that independent scientists can’t confirm the countries’ findings certainly sets off alarm bells following Iraq, but one U.S. official says the massive intelligence failure over Iraq’s WMDs has made U.S. analysts exceptionally careful. “You have to use sophisticated analytic techniques that account for, and carefully weigh, competing evidence and subject your findings to intense self-imposed scrutiny,” the official said. That’s good, but the rest of the world is probably going to need to see some scrutiny that isn’t “self-imposed.”