In an address to the UN Security Council on Friday, Mr. Guterres made an urgent plea for de-escalation, calling the spiralling confrontation a defining moment for the future of global security.

“We are not drifting toward crisis – we are racing toward it,” he said.

“This is a moment that could shape the fate of nations…the expansion of this conflict could ignite a fire no one can control,” he warned.

Widespread panic, destruction

The Secretary-General’s remarks came amid a mounting civilian toll in both Israel and Iran, and as several nuclear sites in Iran have come under direct military assault.

Over 100 targets have been struck across Iran, including military and nuclear infrastructure such as the Natanz and Isfahan nuclear facilities and the Khondab heavy water reactor.

Iranian officials report over 224 civilian deaths, with some estimates twice as high. More than 2,500 have been injured reportedly – while major cities like Tehran have seen mass displacements, fuel shortages and widespread panic.

Iran has responded with its own barrage of missile strikes on Israel, hitting cities such as Tel Aviv, Haifa and Beersheba. Critical civilian sites, including the Soroka Medical Center and the Weizmann research institute, have been damaged. Twenty-four Israelis are confirmed dead, with more than 900 injured.

Give peace a chance

Mr. Guterres urged both parties to give diplomacy a chance, reiterating the need for full Iranian cooperation with the UN nuclear energy watchdog, IAEA, and warning that the “only thing predictable about this conflict is its unpredictability.”

He also called for unity within the Security Council and adherence to the UN Charter.

“The Non-Proliferation Treaty is a cornerstone of international security,” he said. “Iran must respect it. But the only way to bridge the trust gap is through diplomacy – not destruction.”

Regional fallout expanding

Rosemary DiCarlo, UN Under-Secretary-General for political affairs, echoed those concerns, providing a grim overview of the violence and rising human toll.

“The vast majority are civilians,” she said, warning of a “humanitarian crisis in real time.”

The regional fallout is expanding, with airspace restrictions now spanning Lebanon to Iraq. Missiles from Yemen’s Houthi forces have targeted Israel and occupied Palestinian territory, while armed groups in Iraq are reportedly mobilizing.

“Any further expansion of the conflict could have enormous consequences for international peace and security,” Ms. DiCarlo cautioned.

She also highlighted global economic implications, noting that trade through the vital Strait of Hormuz has fallen 15 per cent amid rising tensions.

Grave warnings on nuclear safety

The most alarming update, however, came from IAEA Director General Rafael Grossi, who warned the Council that Israeli attacks on Iranian nuclear facilities are degrading critical safety systems and placing millions at potential radiological risk.

At Natanz, the destruction of electricity infrastructure and direct strikes on enrichment halls have led to internal contamination. While no radiological release has been detected outside the facility, Mr. Grossi warned that uranium compounds now pose significant health hazards within.

At Isfahan, multiple buildings – including a uranium conversion plant and a metal processing facility – were hit. At Arak’s Khondab reactor site, damage was sustained, though the facility was not operational.

The greatest risk, however, is the Bushehr Nuclear Power Plant, which remains operational.

A direct strike, Mr. Grossi warned, “could result in a high release of radioactivity to the environment.”

Millions at risk

Even disruption of its external power supply could lead to a core meltdown. In the worst-case scenario, radiation would affect populations hundreds of kilometres away and require mass evacuations.

Mr. Grossi also warned against any attack on the Tehran Nuclear Research Reactor, which could endanger millions in the capital.

“Nuclear facilities and material must not be shrouded by the fog of war,” he said. “We must maintain communication, transparency and restraint.”

Pledge to stay

Concluding his briefing, Mr. Grossi pledged that the IAEA would continue to monitor and report on nuclear safety conditions in Iran and reiterated his readiness to mediate.

He stressed the agency “can guarantee, through a watertight inspections system,” that nuclear weapons will not be developed in Iran, urging dialogue.

“The alternative is a protracted conflict – and a looming nuclear threat that would erode the global non-proliferation regime.”