Investigating the Allegations of Indian Nuclear Test Preparations in the Rajasthan Desert

A CTB Verification Exercise Using Commercial Satellite Imagery

July 1996

Vipin Gupta and Frank Pabian

From the Original Document at: http://www.ca.sandia.gov/casite/gupta/conclusions.html



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Conclusions


Conclusions and Implications


Our investigation of the nuclear test allegations against India produced a series of small findings that cumulated into a significant overall result. The first discovery was the exact location of the May 18, 1974 nuclear test. This finding made it possible to search for evidence of the reported 1981, 1982, and 1995 nuclear test activity that allegedly took place in the immediate vicinity of the 1974 test location. The search revealed a handful of military sites, including a military range with a secured area surrounded by open desert near Khetolai village. This range - the Khetolai military range - was used for the May 18, 1974 nuclear test and has been the geographic focal point of the subsequent allegations of nuclear test preparations (see plates 7 and 13). Change detection analysis revealed evidence of large-scale, unusual activity at the Khetolai military range. From being relatively unchanged between May 1992 and March 1995, the Khetolai military range transformed into an active site over a one year period; between March 1995 and March 1996, new security perimeters were built, all terrain vehicle traffic noticeably increased, and several, long linear traces were created.

After these new features were found, the conflicting news reports on the activity (or inactivity) in the Pokharan area were checked to determine which factual claims were consistent with the image-derived information. Articles with verified factual claims were deemed as credible, and articles that were inconsistent with the image information were excluded from the analysis (see Appendix C). The credible articles were used along with the image-derived information to determine whether the recent activity at the Khetolai military range was conventional, missile, nuclear, or innocuous. The characteristic signatures of these different activities were identified and compared with each item of evidence in a table of suppositions and a Venn diagram (see Appendix D and figure 3).

The analysis of the Venn diagram led to three main conclusions. First, the Khetolai military range has a history of nuclear test activity. It was used for the May 18, 1974 nuclear test, and there is credible evidence from four different sources that indicates shafts were constructed in the early 1980s for two additional nuclear tests there.

Second, there is believable evidence that supports the claim of planned Prithvi field testing at the Khetolai military range. An Indian news report with four verified factual claims described the planned missile activity, and 1:500,000 scale US DMA maps of the area show five nearby military operation areas that could be well-suited as missile impact points (see figure 5 inset). [80]

Third, a significant fraction of the image-derived evidence was consistent with nuclear test preparations, planned Prithvi missile testing, or a combination of both. This evidence could be spatially linked to other items of evidence that were attributable to either nuclear test preparations or planned Prithvi field testing (see figure 3).

Viewing the collected body of evidence as a whole, it is clear that the Khetolai military range is configured for unconventional purposes. It contains all of the large-scale components for nuclear testing (see figure 4), and several of the large-scale components for field missile testing (see figure 5). Thus, nuclear test preparations and planned Prithvi field testing are each plausible, non-exclusive explanations for the recent activity at the Khetolai military range (see figure 3).



Implications for CTB Verification and Compliance

Besides providing new information on India, our investigation of the nuclear test allegations reveals several lessons that are relevant to future CTB verification and compliance. These lessons apply to two types of organizations: those that are observing others with commercial imaging satellites and those that are observed by others with this technology.

The case study illustrates the need to effectively discriminate nuclear test preparations from other military activities. Just as seismologists need to be adept at discriminating between nuclear explosions and routine mining blasts, image analysts need to be able to discriminate ordinary military exercises from maneuvers used as a cover for nuclear test activity. The ability to tell the difference is particularly important for countries where the military may have an integral role in the state's nuclear test programs.

In our analysis of India, the discrimination problem was an acute one. It was complicated not only by the possibility of more than one type of unconventional test activity in the same area, but also by the technical limitations of the available commercial satellite imagery. There were two principal limiting factors: timing and spatial resolution. Because no commercial images were acquired just before or shortly after the nuclear test allegations were made, it was not possible to determine exactly when certain changes occurred. As a result, no insight could be gained by sequentially observing the numerous changes that did take place. In addition, because all of the old and new images were acquired at moderate spatial resolutions, it was not possible to search for small-scale features. If higher resolution imagery were available, the search for specific objects such as drilling equipment, debris piles, instrumentation trailers, TELs, and missile tracking stations could have yielded more information for the Venn diagram analysis. Moreover, the number, size, and movement of vehicles might have provided useful clues about the level and type of activity that was taking place.

The temporal and spatial limitations of the current commercial imaging satellites illustrate the need for more responsive, higher resolution imaging systems. Fortunately, better satellites are presently under construction and are scheduled for deployment over the next 6 to 18 months. These satellites will acquire panchromatic images at a 1-3 meter ground sample distance and multispectral images at a 4 meter ground sample distance. [81] The companies that will sell these images plan to deliver the digital products within 72 hours of acquisition. If these satellites perform as specified, the CTB verification regime will be enhanced significantly.

Even if the planned technical improvements take place, the high demand for collateral information will remain. As demonstrated in this study, media reports and scientific papers were valuable, sometimes critical, sources of information for the imagery analysis. The villagers' eyewitness accounts and the Indian government's official and unofficial statements were particularly important for determining where to search for the alleged activities.

In countries with a controlled press and restricted academia, it may be more difficult to collect collateral information that is high quality and in sufficient quantity to be useful. Under such adverse circumstances, alternative information sources would have to be utilized, including reports from dissidents, emigrants, the foreign media, human rights organizations, and humanitarian agencies. [82]

As commercial high-resolution satellite imaging becomes more commonplace, nuclear-capable states - particularly the nuclear weapons states - will likely be subjected to an unprecedented amount of overhead observation by numerous governments, non-governmental organizations, and international agencies. With this increased transparency, imaged states will be compelled to avoid non-nuclear activities that could easily be misconstrued as nuclear test preparations - especially activities in sensitive areas such as former nuclear test sites. Failure to do so could inadvertently trigger unwarranted on-site inspection requests that could gradually erode confidence in the treaty. Thus, besides complying with the CTB provisions, state-parties will have the de facto obligation to conduct their sensitive, non-nuclear activities in observably unambiguous ways.



Utility of Commercial Satellite Imagery for CTB Verification

The investigation of the recent Indian nuclear test allegations was done specifically to test the utility of current commercial imaging satellites for CTB verification. In contrast with the previous remote sensing studies of known nuclear test sites, this investigation demonstrated in a realistic CTB scenario how the latest commercial imaging satellites could provide invaluable information for test ban verification before the occurrence of a nuclear test.

The CTB verification exercise empirically showed how commercial satellite imagery filled a critical technical niche in the overall verification regime. With journalists acting as de facto on-site and off-site inspectors for the hypothetical CTB, the satellite imagery was effectively used to check the conflicting factual claims that were made by the media as well as reveal new facts that were not in the news reports. When combined with the credible articles, the image-derived information presented a clearer picture on the nature and extent of the observed activity. Although it did not provide conclusive proof that led to a single unequivocal explanation, the image information did make it possible to conduct a technical analysis and make an informed assessment based on the collected body of evidence.

The investigation provided a glimpse of commercial satellite imagery's future role as an instrument for CTB verification. As the only "pre-test" monitoring technology that will be openly available on the commercial market, it is likely to be used extensively by numerous states to verify compliance with the treaty. States could use the imagery to make a case to the CTBT Organization for an on-site inspection. In addition, the imagery could trigger intensified monitoring of a suspect site with "post-test" technologies - particularly seismic and radionuclide sensors. [83]

The decentralized application of this open source technology will add a new layer of capability to the CTB verification regime. And with the continued improvements in spatial and temporal resolution, commercial imaging satellites will most likely be used to accomplish verification tasks that will be far more sophisticated than the ones that were done for this study. The question for the future is no longer whether commercial satellite imagery will be applied to verify a CTB, but rather what lasting impact will it have on the implementation of the treaty.


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