system
Given the following post, respond as if you're commenting on Reddit:
human
I don't believe that war is ever justifiable. CMV.

For context: I am Canadian.  
  
I'll break this position down into sections from narrow to broad.
  
1. I don't believe that war is ever justifiable for me, personally.  Meaning I would never go to war for my country or to the aid of another country.  The personal cost to my psyche of taking another human life outweighs any ideal of nationalism, defence, or 'aid'.

2. I don't believe that war can be justified in our present global context.  Meaning that any current war or war that might be started in the future is not justifiable.    
I feel that current conflicts are fueled  by constant chest-puffing by countries demonstrating their military fortitude.  Just as the US feels threatened by a country like Iran with a differing national ideology building up a nuclear arsenal, Iran feels threatened by the US's already massive nuclear arsenal.  
Border/Land conflicts where both countries have a legitimate claim should be negotiated to a compromise.  Any attempt to claim/annex new land should be responded to with sanctions and cutting off trade etc.
Any civil conflict where a people uprises against an oppressive ruling power should be non-violent.  Violence perpetrated against the peaceful revolutionaries can/should/will be shown to the world (technological connectedness) and other countries should again respond by cutting off ties, and neighbouring countries taking in refugees.  
In a situation where a country is attacked by the forces of another country, I don't believe that a retaliatory war is justifiable.  Again, cutting ties to the country is the appropriate response.  
A country that shows aggression will not be able to show prolonged aggression if they are shut out of global trade - resources will run dry.

3. I don't believe that any war has ever been justifiable.  I am not a huge history buff, but I truly believe that no war has ever been necessary.

So, to summarize:  
I believe that peaceful solutions are present in any conflict and the choice to go to war is never justifiable.  
Point 3. is most likely to change, then point 2., and point 1. is most likely to remain as it is.  That said, feel free to challenge any or all of my views, and liberally cite any bygone battles, current conflicts, or future fallouts that may support your points!
gpt
I would agree that the beginnings of almost all wars are not justifiable.

But what about WWII when Germany attacked. Should the US have continued to allow the Germans to kill the Jews and the Japanese to slaughter the Chinese? The US tried cutting ties with Japan and Germany but that did not matter.

The US also knew that if they allowed Germany to take over Europe and Japan to rule Asia then it would be only a matter of time before the Axis attacked the US.

Also remember that Europe tried your peaceful means with Germany prior to WWII. They tried to cut of trade and have economic slaps on the wrist. They tried appeasement. And because they pussy footed around millions of innocent unnecessary lives where lost.

Would you rather have had England and France to put up no resistance when Germany came to their borders simply because they were against war?