Make no mistake - the Cold War is back. As with the first Cold War the main task is to ensure that it does not turn hot. Paradoxically, the way to achieve that is for NATO, with all the clarity it can muster, to tell Putin that a move against the Baltic states would be met by military retaliation. It is the message that should come out of the crisis summit which president Obama has called for next week. It's scary, but Putin, like so many of his predecessors, understands all too well the language of force.