The first “cold test” of a weapon (i.e. a test of the implosion using inert natural uranium instead of highly enriched uranium) took place on March 11, 1983 under the leadership of Dr. Ishfaq Ahmed of the PAEC. This test was conducted in tunnels bored in the Kirana Hills near Sargodha, home of the Pakistan Air Force's main air base and the Central Ammunition Depot (CAD).The Kirana Hills test tunnels were reportedly bored by the SDW after the Chagai nuclear test sites, i.e. sometime between 1979 and 1983. As in Chagai, the tunnels had been sealed after construction to await tests. As Prior to the cold tests, an advance team opened and cleaned the tunnels.
Source: http://www.defence.pk/forums/pakist...-pakistans-nuclear-progarm.html#ixzz2T16uWv2W
That information btw was not that secret.. even hollywood had that in mind..
the 1983 movie called "Wargames" showed a secret US scenario in which India and Pakistan went to nuclear war and because of them the US and USSR did.
Had India really pushed for nukes.. the US would have given us a few as well(thru the Chinese).
We were the Israel for South Asia at the time.