Successive US presidents have played into his hands. Bill Clinton, the occupant of the White House when Putin came to power, handed this ultra-nationalist a popular grievance by pushing for the expansion of Nato right up to Russia"s borders. As George F Kennan, the famed architect of America"s Cold War strategy of containment, warned at the time: "Expanding Nato would be the most fateful error of America policy in the entire post-Cold War era."