"but there is no way to "ascertain that the soil samples taken had a direct link to the pictures of the helicopter drops of gas cylinders". Assertions that the sample's chain of custody ensured no tampering are also not verifiable. "Samples with no chain of custody have no value whatsoever," says chemical weapons consultant Jean Pascal Zanders." "Iraqi insurgents have been using it [chlorine] in truck bombs for years, to sow panic among civilians, which may have been the goal in Syria."