A Russian attack on a NATO member cannot be ruled out, Christoph Heusgen, the head of the Munich Security Conference, has said in remarks published on Saturday, days before the gathering of world leaders and defence experts starts. Asked whether he thought Russian President Vladimir Putin could order such an attack, Heusgen responded: “Naturally. Putin has after all said repeatedly that the collapse of the Soviet Union was the greatest catastrophe of the 20th century, because it resulted in many Russians being stranded outside Russia’s borders.” Putin aimed to reestablish a Greater Russia with…