The Security Council convened a session to discuss the war in Ukraine on Tuesday afternoon, on the first day of the General Assembly’s annual summit meeting in New York. Ukraine and its allies intended for the session to signal that the conflict was still a global priority, even as wars in Gaza, Sudan and Myanmar demand attention.

President Volodymyr Zelensky of Ukraine addressed the Council in a brief speech, appealing to its 15 members to continue supporting his country’s fight against Russia, which began a full-scale invasion of Ukraine in February 2022.

“Russia is committing an international crime. This war can’t simply fade away, this war can’t be calmed by talks. Actions are needed,” Mr. Zelensky told the Council. “Russia can only be forced into peace.”

Mr. Zelensky said that Ukraine had obtained information that Russia was planning to attack its three nuclear plants. “We have proof of this, if Russia is ready to go that far, it means nothing you value matters to Moscow.”

He said he had put together a new victory plan based on the principles and values of the U.N. charter, but did not elaborate on its details other than to say that he was organizing a peace conference. He added that he would invite all countries to the conference, including China, Russia’s most powerful partner, and India, which has said it is a neutral player in the war but is helping to sustain Russia’s economy with large oil purchases.

Mr. Zelensky was speaking ahead of meetings this week, during which he plans to present his “victory plan” to President Biden and other U.S. officials. So far, he has withheld details of the plan from the public. Mr. Zelensky has also called for the United States and other allies to permit Ukraine to use long-range missiles provided by the West to strike deep into Russia.