Place a reasonably confident Afghan army at the front, costing $12 billion per year for the next decade, and replace our combat battalions with a U.S. adviser corps of about 25,000. Provide these advisers with incentives (extra pay or promotion) to undertake a frustrating job. No strategy is risk-free, either in the stock market or on the battlefield. But on balance, it’s time to begin a quiet withdrawal of our combat units. It’s not our war to fight if the Taliban are not a threat to the U.S.