The game-changing events in the 2008 campaign are issues of war and peace. Both may be in play between now and November, in ways that add extra volatility to the presidential race. Let's start with war: The United States is already fighting two of them, in Iraq and Afghanistan. But judging from recent statements by administration officials, there is also a small, but growing, chance of conflict with Iran. The administration is signaling the Iranians that they need to stop supplying and training Shiite militias in Iraq -- or run the risk of U.S. retaliation. The Maliki government in Baghdad,...