scientific experiment and sixth nuclear test: codename Chagai-II. There is controversy regarding environmental damage caused by the test, which dismissed by Balochistan media which worked with the government as misinformation, since the test were carried out hundred meters underground of Ras Koh hill and the explosions were not damaging any environment of the any areas in Pakistan or India. Stockpile Estimates of Pakistan's stockpile of nuclear warheads vary. The most recent analysis, published in the Bulletin of the Atomic Scientists in 2010, estimates that Pakistan has 70–90 nuclear warheads. In 2001, the US-based Natural Resources Defense Council (NRDC) estimated that Pakistan had built 24–48 HEU-based nuclear warheads with HEU reserves for 30–52 additional warheads. In 2003, the US Navy Center for Contemporary Conflict estimated that Pakistan possessed between 35 and 95 nuclear warheads, with a median of 60. In 2003, the Carnegie Endowment for International Peace estimated a stockpile of approximately 50 weapons. By contrast, in 2000, US military and intelligence sources estimated that Pakistan's nuclear arsenal may be as large as 100 warheads. In 2018, the Federation of American Scientists estimated that the arsenal was about 120-130 warheads. The actual size of Pakistan's nuclear stockpile is hard for experts to gauge owing to the extreme secrecy which surrounds the program in Pakistan. However, in 2007, retired Pakistan Army's Brigadier-General Feroz Khan, previously second in command at the Strategic Arms Division of Pakistans' Military told a Pakistani newspaper that Pakistan had "about 80 to 120 genuine warheads." Pakistan's first nuclear tests were made in May 1998, when six warheads were tested under codename Chagai-I and Chagai-II. It is reported that the yields from these tests were 12 kt, 30 to 36 kt and four low-yield (below 1 kt) tests. From these tests Pakistan can be estimated to have developed operational warheads of 20 to 25 kt and 150 kt in the shape of low weight compact designs and may have 300–500 kt large-size warheads. The low-yield weapons are probably in nuclear bombs carried on fighter-bombers such as the Dassault Mirage III and fitted to Pakistan's short-range ballistic missiles, while the higher-yield warheads are probably fitted to the Shaheen series and Ghauri series ballistic missiles. Second strike capability According to a US congressional report, Pakistan has addressed issues of survivability in a possible nuclear conflict through second strike capability. Pakistan has been dealing with efforts to develop new weapons and at