Vladimir Putin has issued a direct nuclear warning to the United States. The Russian leader issued a defiant response when asked how he would respond if America sent ground troops to Ukraine. Speaking in an interview on Wednesday (13 Marc), Mr Putin said Moscow was prepared for a nuclear confrontation if there was a threat to Russia’s sovereignty or security. The Russian leader said: “I don’t think that everything is rushing so head on here [with nuclear confrontation], but we are ready for this.”