Are these reasons for going to war justified? My views are:
1) Our country was deliberately attacked by a foreign power or terrorists supported by a foreign power.
Yes
2) Though no attack has yet occurred, there is an imminent and real threat of a foreign power attacking our country.
Yes, though this has to have sufficient proof, not merely suspicion.
3) A foreign power is hostile toward us in its rhetoric, but has shown no clear signs of a planned attack.
No
4) A foreign power is developing nuclear capablities and has shown hostile intentions to another power.
Pakistan and India come to mind. With so much at stake, I doubt that their hostile intentions will lead to anything other than some saber rattling and border skirmishes. So... a conditional no. Yes, only for an expansionist country that should be stopped early.
5) A foreign power is developing nuclear capabilities, but has shown no clear signs of hostile intentions to any other country.
I'm not sure if North Korea falls into this category. My impression is that they want nuclear arms simply to be left alone. Certainly, they have a brutal government but regime change is a dangerous business, that also sets a bad precedent.
6) A brutal dictator rules a country that is a threat to its neighbors, though not to us.
Probably not, unless it will destabilize the world economy and unless a large unity of nations exist to stop this country.
7) A brutal dictator rules a country but is no threat to any other country.
No, unless only to give military aid to an internal rebellion against such a dictator.
8) A foreign power attacks our allies.
Yes, though hopefully joined with other allies.
9) A foreign power attacks another country that is not our ally.
No, unless there is a truly joint and widespread UN effort