These are the conditions under which I, personally, would consider the possibility of the use of force...

1. That, once having formed a coalition with as many countries as possible, there is unanimous agreement on the use of force. In the absense of a coalition, that force is only used if all of our allies agree to it.

2. That any use of force is directed by either the UN, or a body appointed by the coalition consisting of members from all of the nations within the coalition.

3. That all other options have been exhausted prior to resorting to the use of force.

4. That force is only used if it will not cause the destabilization of any country that has a government who is friendly to us or who is willing to help us.

5. That force is used only for strategic purposes, and not in order to demonstrate the superiority of the US over any other nation.

6. That only the absolute minimum amount of force needed to accomplish the goal is used.

7. That the use of force will not set in motion any events that will cause more problems for us in the long run.

8. That the use of force is only for the purpose helping to solve the problem of terrorism, and not for any other purposes (such as to promote a particular political system, or in order to give certain industries a boost)

There may be others, but that's what comes to mind right now.