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3. Potential Impact of Clandestine Foreign Testing: U.S. Security Interests and Concern
Pages 61-78

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From page 61...
... national-security interests and concerns of the degree of foreign nuclear testing that could plausibly occur without detection under a CTBT regime, or, alternatively, through overt testing. Our principal focus here is on the technical question of what additions to their nuclear-weapon capabilities other countries could achieve through nuclear testing at yields that might escape detection, but we give some attention as well to the related military and political question of the impact of such additions on the security interests and freedom of action of the United States.
From page 62...
... These may include a country's motivation to acquire nuclear weapons, as well as its production of or access to plutonium or enriched uranium for fission weapons, the necessary tritium for boosted fission weapons and boosted primaries for thermonuclear weapons, and the lithium-deuteride "salt" that is used in thermonuclear weapons. Another important factor is the means of delivery, some of which impose greater demands on the nuclear-weapon payload.
From page 63...
... security interests and concerns. We then discuss the advances that could plausibly be made by clandestine testing in various yield ranges, under a CTBT, by countries with greater prior nuclear test experience and/or design sophistication and those with lesser experience and/or sophistication.
From page 64...
... , which could lead in turn to nuclear weapons acquisition by Japan, South Korea, and many others. With sufficient testing, many countries would be able to master boosted fission weapons and thermonuclear weapons.
From page 65...
... They typically involve small plates or other shapes formed of plutonium or uranium. Hydrodynamic tests involve material in weapon configuration but are arranged to avoid criticality, either by means of reducing the scale below critical mass or by replacing the plutonium or U-235 with a simulant material.
From page 66...
... The 3-stage Taepo Dong-2, under development but as yet untested by North Korea, could deliver a 700-kg payload anywhere in the United States.3 In summary, if a CTBT was scrupulously observed, nuclear threats to the United States could still evolve and grow, but the range of possibilities would be considerably constrained. Boosted fission weapons and thermonuclear weapons would be confined to the few countries that already possess them and to those to which such weapons might be transferred or to which ~ ~ 1 ~ 1 _ · ~ 1 · ~ 1 ~~ · resigns m~gnt oe communicated worn sur~c~ent precision that a trusting and competent recipient Testimony by R.D.
From page 67...
... Evasive Testing Under a CTBT In the case we now wish to compare to the no-CTBT and rigorously-observed-CTBT reference cases—that of clandestine testing under a CTBT within the limits imposed by the monitoring system we distinguish between two classes of potential cheaters, those with greater prior nuclear test experience and/or design sophistication and those with lesser prior experience and/or sophistication. The purposes and plausible achievements for testing at various yields by countries with little versus extensive prior nuclear test experience are summarized in the following table.
From page 68...
... · limited improvement of efficiency & weight of unboosted fission weapons compared to lst-generation weapons not needing testing · proof tests of compact weapons with yield up to 1-2 kt (with difficulty) · development of low-yield boosted fission weapons · eventual development & full testing of some primaries & low-yield thennonu_ _ clear weapons proof tests of fission weapons with yield up to 20 kt eventual development & full testing of boosted fission weapons & thermonuclear weapons Countries of greater prior nuclear test experience and/or design sophistication same as column to left, plus · limited insights relevant to designs for boosted fission weapons _ one-point safety tests validation of design for unboosted fission weapon with yield in 10-ton range validation of design for unboosted fission weapon with yield in 1 OO-ton range possible overrun range for one-point safety tests · proof tests of compact weapons with yield up to 1-2 kt · partial development of primaries for thermonuclear weapons development of low-yield boosted fission weapons development & full testing of some primaries & low-yield thermonuclear weapons proof tests of fission weapons with yield upto20kt .
From page 69...
... Impossible to Conceal The "high-yield" range in excess of 20 kt would normally be used in the absence of a CTBT to test new configurations of boosted fission weapons or thermonuclear weapons. As discussed above in our treatment of nuclear-test monitoring, any nation with a nuclear explosive could detonate it on a barge or small boat on the open ocean.
From page 70...
... We then take up Pakistan and India—non-participants in the NPT with early-stage nuclear weapon programs and very limited test experience. Finally, we discuss North Korea, Iran, and Iraq, all three of which are NPT members but have been involved in nuclearweapons activities to a varying extent.
From page 71...
... Indeed, with its experience in testing and weapon design, Russia could develop a lO-ton nuclear weapon using only hydronuclear tests in the kilogram-yield range, and be reasonably confident of its performance. Russia might even aim for a lO-ton weapon as a modification of an existing weapon of higher yield, of which it has a surplus.
From page 72...
... . Without a CTBT In the absence of a CTBT, China would be able to conduct nuclear tests in the yield range needed to develop a more nearly optimum (lighter weight and perhaps more efficient use of fissile material)
From page 73...
... It could also master a thermonuclear weapon design with a size and mass compatible with delivery by its missiles. Such tests would with high probability impel Pakistan to resume its nuclear tests and might well provoke a return to testing by China.
From page 74...
... As the table presented earlier indicates, clandestine testing in this size range would permit India to conduct one-point safety tests and, with difficulty, proof tests of weapons with yields up to 1-2 kilotons. But it would not suffice to develop boosted fission weapons or thermonuclear weapons.
From page 75...
... With substantially more plutonium than it is suspected to have diverted in the past from its reactors, North Korea could have a test program leading eventually to a thermonuclear weapon. The resulting reduction in plutonium or U-235 needed for a given yield would increase the number of weapons that could be made from a given stock of fissionable material, and the improved yield-to-weight ratio of thermonuclear weapons would allow a given amount of damage to be done by fewer or lighter long-range missiles.
From page 76...
... An underground nuclear test program might result (or even tests within the atmosphere) , with eventual progression to boosted fission weapons and thermonuclear designs—providing a potential nuclear threat to U.S.
From page 77...
... As regards seismic detection, if Iran or Iraq could manage to construct a decoupling cavity in salt, it might attempt to test evasively at a yield up to ~ to 2 kt. The implications of this for nuclear-weapon development would be similar to the case of North Korea namely, the possibility of progress toward moderate improvements in weight and mater~als-utilization efficiency compared to first-generation fission weapons, and the possibility of proof testing a low-yield fission weapon, but no possibility of achieving the much larger efficiency gains and weight reductions associated with boosting and thermonuclear weapons.
From page 78...
... ~ ~ 7 it_ ~ _=,~ ~ v_—^_— ~^ __ ~r ~~O VYl~~l~ W~U1~ Increase tne pronan~ty ot detection and would be costly in terms of nuclear materials. The inability to test at yields above 1 to 2 kt would preclude the demonstration of boosted fission weapons, of primary nuclear explosives for driving the thermonuclear secondaries of strategic weapons, and the demonstration of thermonuclear weaponry.


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