John J. Mearsheimer and Stephen M. Walt make a powerful case for offshore balancing as a grand strategy for the United States, but, when it comes to Russia and Europe, they refuse to draw the logical consequences of their own framework. As a result, their analysis implodes.   Here’s how Mearsheimer and Walt define offshore balancing: Washington would forgo ambitious efforts to remake other societies and concentrate on what really matters: pre­serving U.S. dominance in the Western Hemisphere and countering potential hegemons in Europe, Northeast Asia, and the Persian Gulf. Instead of policing the world, the United States would encourage other countries to take the lead in checking rising powers, intervening itself only when necessary.   “How would it work?” they ask. Here’s the answer: the United States should