Addressing the Security Council in New York, Mr. Guterres said the latest attacks launched by Russia on 23 and 24 May – and the prospect of additional strikes – underscored “the gravity of this moment.”

“The current course is not sustainable,” he said. “This trajectory must change.”

He warned that the intensifying conflict risked spiralling “out of control,” citing the dangers of miscalculation and “unknown and unintended consequences.”

“What is needed now is de-escalation – immediate and sustained,” the Secretary-General said. “What is needed now is a full and unconditional ceasefire.”

Massive attacks

Russia launched around 90 long-range missiles and 600 drones during the overnight attacks, killing at least five people and injuring more than 100 across Ukraine, with the heaviest damage reported in the capital Kyiv.

Diplomatic premises and compound housing UN agencies were also affected by falling debris, although no UN personnel were injured.

Civilian toll rising

The emergency meeting came amid mounting concern over rising civilian casualties and continued attacks on civilian infrastructure in both Ukraine and Russia.

According to the UN human rights office, OHCHR, more civilians were killed or injured in Ukraine during the first four months of 2026 than during the same period in 2025. The office verified 815 civilian deaths and 4,174 injuries between January and April.

Since Russia’s full-scale invasion began in February 2022, more than 15,000 civilians – including nearly 800 children – have been killed in Ukraine, according to verified UN figures.

Return to negotiations

Earlier in the day, UN High Commissioner for Human Rights Volker Türk called on both sides to return to negotiations.

“I strongly urge restraint. Resume negotiations and end the suffering,” he said.

Mr. Türk cited several recent attacks causing heavy civilian casualties, including a Russian strike on a residential building in Kyiv earlier this month that reportedly killed 24 civilians.

He also referred to a Ukrainian strike on an educational complex in the Russian-occupied city of Starobilsk, which Russian authorities said killed 21 people and injured 44 others.

Publicly available information indicated that civilians, including students, were among the casualties, according to OHCHR.

‘Time for peace is now’

Mr. Guterres reiterated that attacks on civilians and civilian infrastructure violate international humanitarian law and called for renewed diplomatic efforts to achieve “a just, lasting and comprehensive peace” in line with the UN Charter.

“The choice is clear. The responsibility is clear. The time for peace is now,” he said.