This project focuses on the time period of the calendar year 2020. Reference documents are primarily open sources, such as speeches, remarks, votes, working papers delivered at disarmament for a (e.g., NPT Review Conference and preparatory meetings, UN General Assembly, International Atomic Energy Agency (IAEA) General Conference, Conference on Disarmament, Nuclear Security Summit, and the Negotiation Conference on the TPNW), and official documents published by governments and international organizations.

In the evaluation section, a set of objective evaluation criteria is established by which each respective country’s performance is assessed.

The Research Committee of this project recognizes the difficulties, limitations and risks of “scoring” countries’ performances. However, the Committee also considers that an indicative approach is useful to draw attention to nuclear issues, so as to prompt debates over priorities and urgency.

The different numerical values within each category (i.e., nuclear disarmament, nuclear non-proliferation and nuclear security) reflect each activity’s importance within that area, as determined through deliberation by the Research Committee of this project. However, the differences in overall score totals among each of the three categories do not necessarily reflect a category’s relative significance in comparison with others, as it has been driven by the differing number of items surveyed. Thus, the total value assigned to nuclear disarmament (maximum score of 101) does not mean that it is more important than nuclear non-proliferation (maximum score of 61) or nuclear security (maximum score of 41).

Regarding the “number of nuclear weapons” (in the nuclear disarmament section) and the “amount of fissile material usable for nuclear weapons” (in the nuclear security section), the assumption is that the more nuclear weapons or weapons-usable fissile material a country possesses, the greater the task of reducing them and ensuring their security. However, the Research Committee recognizes that “numbers” or “amounts” are not the sole decisive factors. Certainly, other factors—such as implications of missile defense, chemical and biological weapons, conventional force imbalances and a psychological attachment to a minimum overt or covert nuclear weapon capability—also affect the issues and process of nuclear disarmament, non-proliferation and nuclear security. However, such factors were not included in our criteria for evaluation as it was difficult to devise objective scales of the significance of these factors. In addition, in view of the suggestions and comments made with respect to the Hiroshima Report 2013, the Research Committee modified the criteria of the following items: current status of the roles and significance of nuclear weapons in national security strategies and policies; relying on extended nuclear deterrence; and nuclear testing. Since the Hiroshima Report 2014, these items have been negatively graded if applicable.

As there is no way to mathematically compare the various factors contained in the different areas of disarmament, nonproliferation and nuclear security, the evaluations should be taken as indicative of performances in general and not as an exact representation or precise assessment of different countries’ performances.

The Hiroshima Report 2021 maintains basically the same structure and items as previous years’ reports, while one item on the TPNW has been added since the Hiroshima Report 2018. Besides this, since the Hiroshima Report 2019, the Research Committee has added an evaluation item addressing whether the respective countries attended the Hiroshima or Nagasaki Peace Memorial Ceremonies while only attendance at the Hiroshima Peace Memorial Ceremony had been evaluated until the Hiroshima Report 2018. (The maximum score of three points in this item remain the same). Since the Hiroshima Report 2020, increases in the number of possessed nuclear weapons in the previous five years, as well as activities that are not covered by the existing evaluation items but are nevertheless deemed contrary to nuclear disarmament and non-proliferation are also negatively graded, if applicable. Furthermore, in the Hiroshima Report 2021, scale of measurement for a few evaluation criteria in terms of nuclear non-proliferation and nuclear security are slightly modified. (See “Evaluation Points and Criteria” in the Part II.)