An ally of Russian President Vladimir Putin said on Tuesday that the world was probably on the verge of a new world war and the risks of a nuclear confrontation were rising. "The world is sick and quite probably is on the verge of a new world war," Dmitry Medvedev, deputy chairman of Putin's powerful security council, told a conference in Moscow. He said such a new world war was not inevitable but the risks of a nuclear confrontation were growing and more serious than concerns about climate change. Putin says the world faces the most dangerous decade since World War Two. He casts the war in Ukraine as an existential battle with an aggressive and arrogant West, and has said that Russia will use all available means to protect itself against any aggressor. The United States and its allies have condemned Russia's invasion of Ukraine as an imperial land grab. Ukraine has vowed to fight until all Russian troops withdraw from its territory, and says Russian rhetoric on nuclear war is intended to intimidate the West into curbing military aid.