Russia’s top diplomat warned on Saturday against “trying to fight to victory with a nuclear power”, delivering a UN general assembly speech packed with condemnations of what Russia sees as western machinations in Ukraine and elsewhere – including inside the United Nations itself. Three days after Russia’s president, Vladimir Putin, aired a shift in his country’s nuclear doctrine, his foreign minister, Sergei Lavrov, accused the west of using Ukraine – which Russia invaded in February 2022 – as a tool to try “to defeat” Moscow strategically, and “preparing Europe for it to also throw itself into this suicidal escapade”. “I’m not going to talk here about the senselessness and the danger of the very idea of trying to fight to victory with a nuclear power, which is what Russia is,” he said. The specter of nuclear threats and confrontation has hung over the war in Ukraine since its start. Shortly before the invasion, Putin reminded the world that his country was “one of the most powerful nuclear states”, and he put its nuclear forces on high alert shortly thereafter. His nuclear rhetoric has ramped up and toned down at various points since. On Wednesday, Putin said that if attacked by any country supported by a nuclear-armed nation, Russia will consider that a joint attack. He didn’t specify whether that would bring a nuclear response, but he stressed that Russia could use nuclear weapons in response to a conventional assault that posed a “critical threat to our sovereignty”. The United States and the European Union called his statements “irresponsible”. The new posture was seen as a message to the US and other western countries as Ukraine seeks their go-ahead to strike Russia with longer-range weapons. The Biden administration this week announced an additional $2.7bn in military aid for Ukraine, but it doesn’t include the type of long-range arms that Zelenskyy is seeking, nor a green light to use such weapons to strike deep into Russia. There was no immediate response to Lavrov’s address from the US, which had a junior diplomat taking notes in its assembly seat as he spoke. More than two-and-a-half years into the fighting, Russia is making slow but continuing gains in Ukraine’s east. Ukraine has repeatedly struck Russian territory with missiles and drones and embarrassed Moscow with an audacious incursion by troops in a border region last month. The Ukrainian president, Volodymyr Zelenskyy, has pushed what he calls a peace formula to end the war. Provisions include expelling all Russian forces from Ukraine, ensuring accountability for war crimes, freeing prisoners of war and deportees, and more. Lavrov dismissed Zelenskyy’s formula as a “doomed ultimatum”. Meanwhile, Brazil and China have been floating a peace plan that entails holding a peace conference with both Ukraine and Russia and not expanding the battlefield or otherwise escalating fighting. Chinese and Brazilian diplomats have been promoting the plan during the assembly and attracted a dozen other nations, mostly in Africa or Latin America, to join a group of “friends for peace” in Ukraine. Lavrov said at a news conference on Saturday that Russia was ready to provide assistance and advice to the group, adding: “It’s important for their proposals to be underpinned by the realities and not just be taken from some abstract conversations.” He said resolving the conflict hinges on fixing its “root causes” – what Moscow contends is the Kyiv government’s repression of Russian speakers in eastern Ukraine, and Nato’s expansion in eastern Europe over the years, which Russia sees as a threat to its security.