The CTBT prohibits any nuclear weapon test explosion anywhere in the world. The treaty was opened for signature by 187 nation and ratified by 178.
The treaty can not formally enter into force until it is ratified by 44 specific nations, eight of which have yet to do so, India, China, Pakistan, North Korea, Israel, Iran, Egypt and the USA.
How did CTBT came into being:
Between 1945 and1996 more than 2000 nuclear tests were carried out, 1032 out of them were conducted by the USA and 715 of them by Soviet Union, according to UN.
The Radioactive fallout from those tests draw criticism from around the globe. As a result, several attempt to curb the explosive tests were made.
Did the CTBT stop nuclear testing:
Since CTBT 10 nuclear tests have taken place. India conducted two in 1998, Pakistan also in 1998, North Korea in 2006,2009, 2013, 2016 and 2017.
United states last tested in 1972 and China and France in 1996.
Why India refused to sign the CTBT:
India’s decision not to sign the treaty is primarily based on national security considerations. India views nuclear weapons as deterrent against potential security threats from neighbouring countries especially China and Pakistan.
India’s decision is rooted in its desire for equitable and universal nuclear disarmament as well as national security concern.