The prohibition on testing
No state engaged in conduct in 2022 that contravened the TPNW’s prohibition on testing. North Korea, however, the only state known to have engaged in explosive nuclear testing since 1998, was said to be moving towards conducting a new nuclear test as the year drew to a close.
In November 2022, South Korea’s president Yoon Suk-yeol said any new nuclear test by North Korea will be met with an international response ‘not seen in the past’. He also called on China to play a greater role to deter the North's provocations.1
North Korea’s last test detonation occurred in September 2017 and Pyongyang subsequently announced a moratorium on nuclear testing in April 2018, ostensibly destroying its Punggye-ri test site the following month. At the end of 2019, however, North Korea declared an end to its unilateral moratorium, with the change of position reaffirmed in January 2020.2 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.2
A new nuclear test detonation by North Korea would violate UN Security Council resolutions and contravene the Comprehensive Nuclear Test-Ban Treaty (CTBT) as well as, arguably, customary international law, in addition to being incompatible with Article 1(1)(a) of the TPNW.
Since the first nuclear test explosion on 16 July 1945, at least eight states have conducted a total of at least 2,050 nuclear test explosions at dozens of test sites around the world.3 India and Pakistan both exploded nuclear devices in 1998. The United Kingdom undertook its last explosive test in 1991. France completed its last nuclear explosive test in 1996 and completely dismantled its nuclear testing site in the Pacific. The United States conducted its last explosive tests in 1992, but in November 2017 the US government decided to shorten its testing readiness timeline from between 24 and 36 months to between 6 and 10 months ‘for a simple test’.4
China’s last explosive nuclear test was in July 1996, only a few months prior to the adoption of the CTBT by the UN General Assembly.7 The Soviet Union/Russia undertook its last known explosive test in 1990. Speaking in February 2023, a few days before the first anniversary of the Russian invasion of Ukraine, President Putin pledged that Russia would resume nuclear testing should the United States do so first.5
In September 1979, a flash over the Indian Ocean detected by a US satellite (Vela) was suspected of being a South African nuclear test, conducted in collaboration with Israel. This was never confirmed officially by either of these states.6
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.
- All non-explosive forms of testing are outlawed by the prohibition on development in the TPNW.
- All explosive testing also contravenes the Comprehensive Nuclear Test-Ban Treaty (CTBT) (a treaty not yet 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.