The head of a global arms watchdog said Wednesday that "incontrovertible" test results from an alleged chemical strike in Syria showed sarin gas or a similar substance had been used.
Samples from 10 victims of the April 4 attack on Khan Sheikhun analysed at four laboratories  "indicate exposure to sarin or a sarin-like substance ... the analytical results already obtained are incontrovertible," said Ahmet Uzumcu, head of the Organisation for the Prohibition of Chemical Weapons.