UNITED NATIONS (AP) — The United Nations chief condemned the U.S.-Israeli airstrikes on Iran and called for an immediate return to negotiations “to pull the region, and our world, back from the brink.”

Secretary-General António Guterres told an emergency meeting of the U.N. Security Council on Saturday that everything must be done to prevent further escalation. “The alternative,” he warned, “is a potential wider conflict with grave consequences for civilians and regional stability.”

Guterres also condemned Iran’s retaliatory attacks for violating the sovereignty and territorial integrity of Bahrain, Iraq, Jordan, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates.

Israel’s U.N. Ambassador Danny Danon, speaking to reporters before the meeting, said it was “hypocrisy” to condemn the airstrikes. He said Iran is responsible for the actions of its proxies in the Middle East and for its nuclear and missile programs, and Israel and the U.S. acted “to prevent an irreversible and immediate threat.”

The attack on Iran killed Supreme Leader Ayatollah Ali Khamenei, The Associated Press has reported. The assassination of the second leader of the Islamic Republic, who had no designated successor, raised the prospects of a protracted conflict given Iranian threats of retaliation. President Donald Trump on social media called his passing “the single greatest chance for the Iranian people to take back their Country.”