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Dr Roshan Khanijo Writes : For some time now, the United States and China have engaged acrimoniously in theatrical fashion regarding the U.S.-China trade war and the Covid -19 Pandemic. This strategic mistrust between the two countries has been further heightened by the U.S. allegations that China has conducted a low yield nuclear test.

Dr Roshan Khanijo Writes :

For some time now, the United States and China have engaged acrimoniously in theatrical fashion regarding the U.S.-China trade war and the Covid -19 Pandemic. This strategic mistrust between the two countries has been further heightened by the U.S. allegations that China has conducted a low yield nuclear test. A few days ago, the Wall street Journal featured an article titled “Possible Nuclear Testing Stirs U.S. Concerns”. The author was potentially referring to a U.S. Executive Summary report from 2020 on the ‘Adherence to and compliance with Arms Control, Nonproliferation and Disarmament Agreements and Commitments (Compliance Report)’. While China was quick to refute these claims, there remain several unanswered questions. Is China’s denial at such a critical moment plausible? If the test did take place, was it a low yield test or a subcritical test? Was the CTBT’s monitoring agency able to detect it? Should sub-critical tests be allowed? etc. This article tries to analyse a few of these concerns.

U.S. Executive Summary Report 2020

The U.S. Executive Summary Report 2020 states that “China maintained a high level of activity at its Lop Nur nuclear weapons test site throughout 2019.  China’s possible preparation to operate its Lop Nur test site year-round, its use of explosive containment chambers, extensive excavation activities at Lop Nur, and lack of transparency on its nuclear testing activities – which has included frequently blocking the flow of data from its International Monitoring System (IMS) stations to the International Data Center operated by the Preparatory Commission for the Comprehensive Nuclear Test-Ban Treaty Organization – raise concerns regarding its adherence to the “zero yield” standard adhered to by the United States, the United Kingdom, and France in their respective nuclear weapons testing moratoria[1].” These claims cast serious aspersions on China’s commitment to nuclear moratorium and de-escalation and should be examined in further detail. However, on the flipside, several of the claims made in the report can be considered as circumstantial evidence as opposed to concrete proof. Furthermore, the report’s allegation, that China  has been blocking the flow of data from its International Monitoring System (IMS) stations has also been refuted by a spokeswoman for the Comprehensive Test Ban Treaty Organization (CTBTO) – which verifies compliance with the pact. The spokeswoman reported that there have been no interruptions in data transmissions from China’s five sensor stations since September 2019[2]. This, then begs the question, that if the report’s initial claims are true, and despite the uninterrupted data transmission, a certain amount of nuclear activity has been observed in China’s Lop Nur test site, can said activity be attributed to China’s conduction of a sub-critical test? And if so, should CTBTO allow such a test in the first place.

CTBTO: Verification and Sub Critical Test

The Comprehensive Test Ban Treaty Organization or CTBTO bans all nuclear explosions on Earth whether for military or peaceful purposes[3]. U.S and China have both signed the treaty but neither has agreed to ratify it. As a result the extremely crucial ‘On-site Inspection’ clause cannot be executed, causing an inability to verify whether or not a nuclear explosion has been carried out by either country by visiting the alleged site. Without visiting the site and analysing the residue, it would be impossible to affirm whether or not a breach has definitively taken place. This particular caveat can only be implemented if the treaty enters into force hence the loophole remains for now.

On site verification aside, there is another aspect of the treaty that is worth examining. While the treaty bans outright nuclear explosions it nevertheless allows sub critical tests. The definition of a sub-critical test is “ nuclear weapons related testing which purposely results in no yield is known as sub-critical testing, referring to the absence of a critical mass of fissile material such a test is not considered a nuclear test[4]” The definition was amended in this manner as some of the Nuclear Weapon State (NWS) insisted on it. Hence, in simpler terms, the CTBTO allows only a zero yield test ban. The reason these nuances matter, is that sufficiently developed Nuclear Weapons States with advanced technologies could continue to improve and augment their nuclear arsenal through sub-critical testing[5]. Furthermore, more complex manoeuvres such as computer simulations, hydrondynamic experiments and inertial confinement fusion experiments, all these activities might allow NWS to modernise their nuclear weapons without explosive testing[6]. The main purpose of sub-critical experiments is to identify and decrease uncertainties in weapon performance[7] while improving nuclear weapons designs. In the long run, these sub-critical tests end up aiding the manufacturers in developing new weapons and addressing the problem of aging weapons and the problems related to their maintenance, as opposed to decreasing and de-escalating.

U.S., Russia and China have all been conducting these tests for a while now, and the probability of China conducting such a test last year cannot be completely ruled out. Especially given the fact that China’s major objective until now has been to modernise its nuclear arsenal and they have been fairly successful in this endeavour thus far. As a result, the arms race is no longer spoken about in dyads. It is instead referred to in a tripolar manner as China’s modernisation spree has made it a central figure of disarmament talks. The New Strategic Arms Reduction Treaty between the U.S. and Russia expires next year unless it is jointly extended by the two countries. At present, U.S. has indicated that it would like China to join in these endeavours as well, thereby converting it into a triparty treaty. China has been reluctant to commit to such a treaty so far as they believe that advancement of their nuclear program is essential and the weapons are for defensive purposes. While these claims are factually exaggerated given China’s hegemonic and dominant relation with its neighbours, it remains relatively reluctant to commit to protracted de-escalation and monitoring for now.

Implications for India 

Although India supports the zero-yield ban, given its precarious geostrategic position it has not signed the CTBTO. Despite not being a signatory to the treaty, India remains hopeful about de-escalation efforts and maintains its optimism regarding the formation of a time bound programme for the complete elimination of nuclear weapons. India has also voluntarily stated that it will not conduct any further nuclear testing. However, China’s recent actions and the activity cited at its nuclear site, will make it essential for India to re-evaluate its policy options. Given the geostrategic rivalry between the two countries, and the widening military gap between them, India’s defensive arsenal might not be sufficient for deterrence maintenance. While India might not want to opt for a full explosive test, given its stance on nuclear de-escalation, sitting by and idly allowing other countries to take advantage of the present loophole is not a reasonable strategic option. In order to maintain the nuclear balance and credible deterrence, the only feasible option left for India is to undertake sub-critical testing as well. India has previously indicated that it is not averse to pursuing this option should the current balance be adversely affected. Furthermore, India already has the technical capabilities required to opt for this option. Given the aging state of the Indian Weapons Systems, and the fact that it already possesses the super computers necessary to model sub-critical tests, it has now become essential to give the latter option some serious contemplation. As Mr Bharat Karnad the nuclear strategists also states that “the laser inertial confinement fusion facility at the centre for advanced technology, Indore, needs to be refurbished on a war-footing, and a dual-axis radiographic hydrodynamic test facility constructed”[8].


 In the past the U.S. Strategic Commission reports have stated that “Apparently Russia and possibly China are conducting low yield tests[9].” However, the fact remains that all three countries have been conducting sub-critical tests, and the construction of new weapon design with different yields, is testimony to this. The insistence of the sub-critical clause by the NWS was intended to favour technically advanced and developed countries. Now nations are trying to create a loophole within a loophole by pointing fingers at other signatories, while doing the same thing themselves. Given the international pressure, there is no true transparency in this area. Without complete transparency, there is no possibility for de-escalation. The comity of nations is, instead, moving towards a dystopian Hobbesian world of International disorder where the rules are dictated and maintained by the mighty who have achieved that power by flouting the rules themselves. Until true commitment to de-escalation and disarmament is evinced by the Nuclear Weapons States with the most arsenal, India should use the window to make sure that it does enough to maintain credible deterrence. This has become particularly crucial today as some of the Indian Weapons Systems are over 20 years old. If it does not find innovative ways of keeping up with  the more advanced NWS, credibly nuclear deterrence will no longer be an option thereby upsetting the geostrategic balance of the entire region. Therefore, sub-critical tests may aid in the maintenance and construction of new designs and hence should be contemplated seriously.

End Notes

 [1] Executive Summary report of the 2020 on the ‘Adherence to and compliance with Arms Control, Nonproliferation and Disarmament Agreements and Commitments (Compliance Report), Bureau of Arms Control, Verification and Compliance at

[2] Julian Borger, “China may have conducted low-level nuclear test, US claims” The Guardian, April 16, 2020 at

[3] CTBTO Treaty at

[4] Nuclear Testing at

[5] Debating the basic issue at

[6] Ibid

[7] Jason ‘Subcritical Nuclear Tests’, Federation of Atomic Scientists at

[8] Mr. Bharat Karnard, “India must revise its nuclear policy and keep its strategy opaque”, Hindustan Times May 11, 2018, at ttps://

[9] William J. Perry and James R. Schlesinger, America’s Strategic Posture – The Final Report of the Congressional Commission on the Strategic Posture of the United States, (Washington D.C.: U.S. Institute of Peace, 2009), p. 83, available at


Dr Roshan Khanijo is the Assistant Director (Research) at the Centre for Strategic Studies and Simulation (CS3), USI of India. She is the resident expert on CBRN issues and has a very large number of publications in Indian and Foreign Journals.
Disclaimer: The views expressed are those of the author and do not necessarily represent the views of the organisation that he/she belongs to or of the USI of India.

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