Back in the 1980s the United States had a doctrine that served as a quick test to be used before the use of military force. It was called the Weinberger Doctrine, and the idea was that before forces were committed the situation needed to meet criteria:
1. Forces should not be committed unless the vital interests of the U.S. or its allied are involved.
2. Forces should be committed wholeheartedly only with the intention of winning.
3. Forces only with clearly defined objectives, and the means to achieve those objectives.
4. The size and composition of the force should be constantly reassessed and adjusted as necessary.
5. Forces should only be committed to battle only with a reasonable assurance of the support of the Congress and the American people.
6. The commitment of military forces should only be considered as a last resort.
Later on it became simplified by Colin Powell and bore his name as the Powell Doctrine:
1. Military force should only be used as a last resort. Only if there is a clear risk to national security by the intended target.
2. Force, when used, should be overwhelming and disproportionate to the force used by the enemy.
3.There must be strong support for the campaign by the general public.
4. There must be a plan for disengagement of forces.
Both are quality doctrines, and should be written in stone at the Pentagon and on the wall of the Cabinet Room in the White House. However, there are other questions that should be addressed in advance of future conflicts.
1. What happens after we win? - Okay, so we kick Yomommastan's ass and our tanks are patrolling their capitol. Now what? We have to feed people, stand up a police force, pick up the garbage, get the electricity/water/phones working, and keep the peace. That is expensive, and labor intensive. Forget the larger strategic issues like: Did we just make life easier for the dictator next door, or did we just make a 50 year military commitment? We need to focus on getting life back to normal as quickly as possible so that the people get back to work ASAP. The faster things get back to a normal standing the faster we can leave. Plus, if people have jobs then they aren't free to join an insurgency.
2.Do we even want to win? Is it worth it in the long run? - There is just no way to look cool while beating the crap out of some third world country. You never hear about the U.S. intervention in Panama back in 1989 and the main reason is that it seemed like a difficult victory to "Feel Good" about. The Panamanians were not match for US forces, and during the initial invasion the slum area around the international airport was burned to the ground. Even though it is a prime example of the Powell Doctrine, "Operation Just Cause" has dropped off the radar of armchair generals and even the Department of Defence. 20 years later, Panama is a thriving democracy with a healthy economy. All of that was made possible by the removal of General Manuel Noriega by the United States. For all of the whining by the anti-war left, the United States lived up to its treaty obligations and handed the canal over to the Panamanian government, stuck it's colors and went home. It was a worthwhile endeavor.
3. Have we done our homework? - Are we really going to be welcomed as liberators? Is there a social dynamic that we might be missing that is going to cause problems while we occupy the country? Is our intelligence as solid as it can be?
4. Do our Rules of Engagement (ROE) make things more difficult for our forces and easier for the enemy? - In Vietnam we had sanctuary zones that were off limit to air strikes and other US attacks. The enemy knew this and took advantage of those areas to stage attacks. In Afghanistan we cannot bomb mosques, so the enemy uses them to hide out in, and in Iraq they used the minarets to coordinate attack on US troops. When you invade another county you are going to piss people off anyway. It is hard to say that you are sensitive to a culture while you blow up everything except the local mosque.