China warned of a potential “catastrophe” while forced on Wednesday to defend its veto last month of a United Nations Security Council resolution that would have punished North Korea for its latest intercontinental ballistic missile tests. The rare UN debate came as officials in Washington, Seoul and the International Atomic Energy Agency warned that Pyongyang might be preparing an imminent nuclear test, which would be the country’s seventh. “China always engages in the work of the Security Council in a responsible manner,” Zhang Jun, China’s ambassador to the UN, said in a speech that blamed the US for stoking tensions in Asia but did not mention any of North Korea’s numerous recent weapons tests. “Under the current circumstances, all parties should remain calm,” he said, adding: “It will be precisely irresponsible and derelict of duty for the Security Council to adopt a resolution without principle, which could result in serious consequences and plunge the countries and regions concerned into a catastrophe.” The public response from Beijing – as well as from Moscow – was the first of its kind at the UN, after a new rule was passed in April requiring an accounting in the General Assembly whenever a permanent member of the Security Council wields its veto. The rule change came amid criticism at the UN after Russia used its veto power on the council to block a resolution condemning its own invasion of Ukraine. The General Assembly does not have the authority to override a Security Council veto, however. United Nations General Assembly will subject any Security Council veto to debate The debate on Wednesday highlighted yet another dispute between Washington and Beijing – though over an issue that US officials insist remains an area where the US and China can cooperate. “It’s hard for me to imagine that Beijing would actually want North Korea to continue to provoke, violate multiple Security Council resolutions, and destabilise the region,” Sung Kim, the US special envoy for North Korea, said on Tuesday. “So we hope that China will be more forthcoming in working with us to deal with the situation on the peninsula.” The Security Council includes five permanent members and 10 rotating members. Only the permanent members – Britain, China, France, Russia and the US – have the power to cast vetoes. China and Russia blocked the Security Council resolution on May 26 targeting North Korea for new sanctions, which would have further restricted Pyongyang’s legal routes for trade and its ability to import key resources like oil. Representing the US at the General Assembly, Ambassador Jeffrey DeLaurentis called China’s explanation of its veto “insufficient, not credible and not convincing”. “Earlier this year, Russia and China pledged a ‘no limits partnership’,” DeLaurentis added. “We hope these vetoes are not a reflection of that project.” South Korea and US stage rare drills with aircraft carrier Proponents of sanctions say they are necessary because North Korea diverts resources that its population desperately needs to its weapons programme and to the country’s elite. Opponents say the sanctions unfairly hurt the country’s already poor and malnourished population. “It’s futile to expect Pyongyang to unconditionally disarm under the threat of a spiral of sanctions,” said Anna Evstigneeva, the deputy ambassador from Russia, which is facing its own punishing sanctions for its invasion of Ukraine. South Korea’s representative, Cho Hyun, countered that North Korea’s “humanitarian suffering comes from state policy, not the ensuing sanctions”. As recently as 2017, China and Russia both sided with the US in punishing North Korea with sweeping economic sanctions after Pyongyang conducted major weapons tests. In the years since, though, both have changed their stance and have tried to push the UN to lift the sanctions. The US has refused because it says Pyongyang has taken no meaningful action to end its nuclear weapons programme, the reason for the sanctions in the first place. Beijing often says it opposes sanctions generally, and emphasised that point on Wednesday – although it is frequently accused of using its own economic might to punish countries with which it disagrees. This year, North Korea has already launched 31 ballistic missiles, according to the US – more than ever before. Eight of those launches took place on Sunday. On Monday, the US and South Korea jointly conducted eight ballistic missile launches of their own in response. The following day, they conducted a joint air drill with 20 warplanes. The US says it has reached out repeatedly to North Korea through multiple channels in a bid to restart a dialogue, but has gotten no response. North Korea has also test-launched intercontinental ballistic missiles twice this year, the US said, which in theory can travel thousands of miles. And officials in the US, South Korea and IAEA have warned that Pyongyang may be gearing up for another nuclear weapon test at any moment. “The DPRK’s senior officials have used rhetoric that could suggest the use of tactical nuclear weapons,” Kim said on Tuesday. At the session on Wednesday, North Korea’s envoy to the UN, Kim Song, said that his country was merely exercising its right to self-defence in the face of a hostile US. He called it a right that “no one can deny”. The UN debate came on the same day that US Deputy Secretary of State Wendy Sherman was meeting in Seoul with her Korean and Japanese counterparts – part of the Biden administration’s plan to boost “trilateral” cooperation as the region grows ever more wary of China and braces for a potential North Korean nuclear test. In a joint statement, the three said that Sherman had “reaffirmed the United States’ steadfast commitments to the defence of the Republic of Korea and Japan, including extended deterrence”. The officials urged North Korea to “engage in dialogue toward the complete denuclearisation of the Korean peninsula”, the statement said.