On May 28, 1998, Pakistan announced that it had conducted five underground
nuclear tests; it announced a sixth test on May 30. Yield estimates of the tests varied
widely. A.Q. Khan reportedly said one of the tests of May 28 had a yield of 30 to 35
kilotons, about twice that of the Hiroshima bomb.38 Samar Mobarik Mand, said to
be "the scientist who conducted Pakistan's nuclear test programme," reportedly placed
the yield of the May 28 tests at 40 to 45 kilotons, and that of the May 30 test at 15
to 18 kilotons.39 On the other hand, estimates based on seismic data placed the yield
of the May 28 tests at between eight and 15 kilotons.40 U.S. officials reportedly
"estimated the cumulative force of the Pakistani blast or blasts [of May 28] at between41
2 kilotons and 12 kilotons, and most likely 6 kilotons ..." For the May 30 test, some
reports placed the yield between 12 and 18 kilotons, but the CIA was said to have
estimated the yield at between one and five kilotons.42 Seismic data indicated a yield
of between zero (no detectable signal) and one kiloton.43 A later analysis by
seismologist Terry Wallace placed the yield of the May 28 explosion (or explosions)
at 9 to 12 kt, and that of the May 30 explosion at 4 to 6 kt.44
37 Tim Weiner, "U.S. and China Helped Pakistan Build Its Bomb," New York Times, June 1,
1998: 6.
38 John Kifner, "Pakistan Sets Off Atom Test Again, but Urges 'Peace,'" New York Times,
May 31, 1998: 8.
39 Tahir Ikram, "Pakistan Has New Missiles To Test — Reports," Reuters newswire, June
1, 1998, 4:15 A.M. Eastern Time.
40 William Broad, "Experts Say Pakistan Test Was Either Small or a Failure," New York
Times, May 31, 1998: 8.
41 R. Jeffrey Smith, "Analysts Skeptical of Pakistan's Claims," Washington Post, May 29,
1998: 33.
42 John Kifner, "Pakistan Sets Off Atom Test Again, but Urges 'Peace,'" New York Times,
May 31, 1998: 1.
43 William Broad, "Experts Say Pakistan Test Was Either Small or a Failure," New York
Times, May 31, 1998: 8.
44 Wallace, "The May 1998 India and Pakistan Nuclear Tests."
While Pakistani statements and seismic data agree that there was only one test
on May 30, the number held on May 28 is disputed. In early reports of May 28,
Pakistan claimed two or three tests,45 a number it quickly revised to five.46 U.S.
analysts questioned the higher number. "Instead of five, 'it appears at least two'
bombs were tested, said one U.S. intelligence official..."47 Similarly, the New York
Times reported that "American intelligence officials said Pakistan had probably tested
only two weapons rather than the five announced."48 Wallace found seismic signals
that could correspond to two explosions, but discounts the plausibility of the second
one. 49
Because the yield appears lower than announced, it is unclear if the devices
performed as intended. According to a press report, U.S. officials said that the
estimated yield of the Pakistani test or tests of May 28, put by that report at most
likely six kilotons, "is less than what U.S. intelligence experts had estimated as the
likely yield of even one of the principal bombs in Pakistan's arsenal, raising questions
about whether the device or devices exploded by Pakistan had performed as
expected."5
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