U.S. envoy to Syria Jim Jeffrey said on Thursday that there is "lots of evidence that chemical weapons" are being prepared by the Assad regime to use in Syria, NPR reports.

Why it matters: The U.S. said this week that chemical weapons are a red line, and will be met with a response "swiftly and appropriately" if used. Presidents from Iran, Russia, and Turkey are meeting today to discuss steps forward in Idlib, which is the last major opposition stronghold in Syria, and could devolve into another major humanitarian disaster.