 However, no warhead was observed at the impact site and none of the 13 environmental samples taken in the Western Ghouta area tested positive for sarin, although three had "degradation and/or by-products" possibly originating from sarin.On 18 September, the Russian Presidential Chief of Staff Sergei Ivanov commented on the U.N. missions findings.He said "these rockets were supplied to dozens of countries", but that "the Soviet Union never supplied warheads with sarin to anyone".