Maybe natural selection? the virgins awaiting the martyrs?, depends on your religion ;P! Ultimately.. they don't need to think or have a reason anyway.

There is not true justification. There are simply false ones. All you do is plant the notion of "enemy of the nation" in people's heads. Russia with its communist history should understand that only too well. The Chinese have this malady, too. Not to mention the obvious insanity of the extreme Islamist.

War can be justifyed only when it defends human rights; especially right to live free but in defense...not to gain oil or something. Anything more than that is not justifyed... each war make more brain washed people who want fight against someone...more we avoid wars..less people die (even innecent ones; civilists)! I think soldiers don't think...if they think at all...If they think then they are not good enough for army. That is what military does...make soldiers dumb...coz you have to be dumb to train for killing people. They think in way like hunters hunt animals: "oh gosh...if I wouldn't kill you then I would die...so its ok" "its either me or you"...like that.. If they are in peaceful country and have to kill people...I think they are brian washed before going to such mission...governments have a lot of tricks to use to make themselve look as victims.

When their weapon argument does not have the place to sell, energy contention, racial conflict and so on

I call it ego. There are different levels of it: personal, of countries in the case of wars, and of humanity. It can be resumed in the belief that the world, the All, belong to me, everything belongs to me as long as i can take what i want from me. This belief can be conscious but i think it´s mostly unconscious. And it doesn't aknowledge that we also, and foremost, belong to the others and to the all. To ilustrate this point i like to think in a videogame: in the way the world of a videogame is concieved. In, say, Zelda, Link, and in last instance the player, feels that the world of Zelda's Videogame is totally theirs, there is no truly worry about the world beside the rules i have to follow to get the satisfaction of the game. And finally in Zelda's world, unlike in ours, our existence doesn't end in the world, we finish the game and our existence continues elsewhere. We think the same about this world, but thats obviously a falacy