Russia's Foreign Minister Sergei Lavrov on Thursday accused Western politicians of fixating on nuclear war, one week after Moscow launched its invasion of Ukraine."It is clear that World War Three can only be nuclear," Lavrov said in an online interview with Russian and foreign media."I would like to point out that it's in the heads of Western politicians that the idea of a nuclear war is spinning constantly, and not in the heads of Russians," he said."Therefore I assure you that we will not allow any provocations to throw us off balance," Lavrov added.On Sunday, Russian President Vladimir Putin ordered Russia's nuclear forces be put on high alert, accusing the West of taking "unfriendly" steps against his country.Moscow has the world's largest arsenal of nuclear weapons and a huge cache of ballistic missiles which form the backbone of the country's deterrence forces.