The prohibition on testing
No state acted in contravention of the TPNW’s prohibition on testing of nuclear weapons in 2023. That said, risks of a new nuclear test detonation were increasing at the time of writing. A nuclear test site in North Korea remained prepared to support a nuclear test, and China, Russia, and the United States have all been engaging in new construction at their respective testing sites and maintain at least some degree of readiness for possible future nuclear testing. In November 2023, Russia withdrew its ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT).
The most likely state to conduct a nuclear test detonation is North Korea, the only state to do so since 1998. Its last nuclear test detonation occurred in September 2017. Pyongyang subsequently announced a moratorium on nuclear testing in April 2018, ostensibly destroying its Punggye-ri test site the following month. But at the end of 2019, North Korea declared an end to its unilateral moratorium, with the change of position reaffirmed in January 2020. At the end of April 2022, there were signs that North Korea was rebuilding tunnels at the site. In mid-December 2022, the South Korean Prime Minister, Han Duck-soo, said publicly that the North was ‘ready’ to test a nuclear explosive device. Warnings that it would do so in 2023 proved unfounded, however.
In March 2023, the International Atomic Energy Agency (IAEA) stated that the site at Punggye-ri remains prepared to support a nuclear test, that it continued to see indications of activity, and that ‘the reopening of the nuclear test site is deeply troubling’. A new nuclear test detonation by North Korea would violate UN Security Council resolutions and contravene the CTBT as well as, arguably, customary international law, in addition to being incompatible with Article 1(1)(a) of the TPNW.
For more information, see the 2023 edition of the Nuclear Weapons Ban Monitor.
Each State Party undertakes never under any circumstances to: ‘test […] nuclear weapons or other nuclear explosive devices.
- The prohibition on testing in Article 1(1)(a) of the TPNW bans the detonation of a nuclear weapon or other nuclear explosive device. It is therefore limited to explosive testing involving a nuclear chain reaction.
- All non-explosive forms of nuclear testing and the testing of missiles designed to carry nuclear warheads are outlawed by the prohibition on development in the TPNW.
- All explosive nuclear testing also contravenes the CTBT (a treaty not in force) and, arguably, customary international law.
- The preamble of the TPNW recognises ‘the vital importance’ of the CTBT and its verification regime as a core element of the nuclear disarmament and non-proliferation regime.
- The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) does not prohibit the testing of nuclear weapons by the five nuclear-weapon states.