An agreement to ban testing
Testing of nuclear weapons in the atmosphere, in outer space and under water was banned in 1963:
(Partial Test Ban Treaty). See: http://fas.org/nuke/control/ltbt/index.html
Underground testing of nuclear weapons was banned on September 24, 1996 under the Comprehensive Test Ban Treaty (the CTBT). See: http://www.fas.org/nuke/control/ctbt/text/ctbt1.htm
BUT, the CTBT will not enter into force until 44 states ratify it – including India and Pakistan.
AND the spirit of the CTBT prohibition has not been respected by the United States as they have continued modernization of weapons through
subcritical tests or
Despite the fact the Treaty has not entered into force, funding has been secured for the Preparatory Commission of the CTBT Organization. Much of the monitoring required pursuant to the Treaty is already occurring. For more information go to: http://www.ctbto.org