That's a no-brainer...

OTHER MUSLIMS!

1) During the Iran-Iraq War (1980-1988), Iraq engaged in chemical warfare against Iran on
multiple occasions, including more than 30 targeted attacks on Iranian civilians.

2) Egypt's chemical weapons program is the most developed of its pursuit of developing a
weapons of mass destruction program though it is thought this reached its peak in the
1960s. It also used chemical weapons during the North Yemeni Civil War. Phosgene and
mustard gas were used against Royalist forces and civilians in Northern Yemen.

3) The Ghouta chemical attack, was a chemical attack carried out by the forces of Syrian
President Bashar al-Assad, in the early hours of 21 August 2013 in Ghouta, Syria during
the Syrian civil war.[17] Two opposition-controlled areas in the suburbs around Damascus
were struck by rockets containing the chemical agent sarin.

4) Senior U.S. officials report that ISIS forces used mustard gas on August 11, 2015
against Kurdish Peshmerga fighters in the region, potentially giving the religious
extremist group a new advantage in the battlefield against their principal rivals.

(did I miss anything?)