Remember the Powell doctrine? Elaborated by Colin Powell back in 1990, during his tenure as chairman of the Joint Chiefs of Staff, it consisted of a series of questions identifying the conditions that should be met before committing U.S. military forces to battle. The questions were: 1. Is a vital national security interest threatened? 2. Do we have a clear attainable objective? 3. Have the risks and costs been fully and frankly analyzed? 4. Have all other nonviolent policy means been fully exhausted? 5. Is there a plausible exit strategy to avoid endless entanglement? 6. Have the consequences of our...