Question: When did the united nations ban chemical weapons?
qaPairs: question: When did the united nations ban chemical weapons by calling for all states to strictly observe the Geneva protocol?
answer: 1966
question: When did the united nations ban chemical weapons with the Chemical Weapons Convention signing?
answer: 13 January 1993
question: When did the united nations ban chemical weapons with the Chemical Weapons Convention becoming effective?
answer: 29 April 1997