The first use of the term " weapon of mass destruction " on record is by Cosmo Gordon Lang , Archbishop of Canterbury , in 1937 in reference to the aerial bombardment of Guernica , Spain : At the time , nuclear weapons had not been developed . Japan conducted research on biological weapons ( see Unit 731 ) , and chemical weapons had seen wide battlefield use in World War I . They were outlawed by the Geneva Protocol of 1925 . Italy used mustard agent against civilians and soldiers in Ethiopia in 1935 – 36
Unit 731
Unit 731
Weapon of mass destruction