Insults, accusations and talk of war crimes and nuclear holocaust dominated the world’s premier diplomatic stage on Thursday, as the United Nations Security Council met to debate how and whether anyone would be held accountable for the war in Ukraine.

Russia’s foreign minister, Sergey Lavrov called Ukraine’s president, Volodymyr Zelensky, a “bastard,” but was not around long enough to hear what many of his counterparts had to say. After arriving 90 minutes late to the meeting — and missing the briefings given by António Guterres, the U.N. secretary general, and Karim Khan, Prosecutor of the International Criminal Court — Mr. Lavrov left early.

The U.S. secretary of state, Antony J. Blinken, denounced President Vladimir V. Putin of Russia for saying on Wednesday that he could use all arms available to him in the war, interpreted by officials in both Russia and the West as a veiled reference to nuclear weapons.

“Every council member should send a clear message that these reckless nuclear threats must stop immediately,” Mr. Blinken told the Security Council, in some of his sharpest comments since the war began. “Tell President Putin to stop the horror he started.”

“One man chose this war. One man can end it,” he added. “Because if Russia stops fighting, the war ends. If Ukraine stops fighting, Ukraine ends.”

See omnystudio.com/listener for privacy information.