Tonight I saw on TV smiling faces of Israeli solders making "victory" signs...
I never was able to understand that...and during Balkan wars of 90s when ever I saw smiling face of a solder coming from " battle" I felt sorry for him...

I was saying that in fact it is NOT hard to understand such smiling - it's relief at being out of it and being alive - and not in itself a sign that they are not "normal" - whatever that is.

Of course war can damage people - to varying degrees, but it's important to remember that not all people in the military are in the front line and not even all of those kill others. Of course, for those who do, or witness it, it can be traumatic:

A nationwide, long-term study of Vietnam veterans -- now entering its third phase -- concluded that one-third of combat soldiers returned emotionally wounded. After the 1991 Persian Gulf War, about 10 percent of the troops suffered distress from a conflict that was much briefer and less intense.

Given the confusing, urban ambush-style fighting in this Iraq campaign, experts predict trauma levels closer to Vietnam's.

...

Fifteen years after being discharged, the post-Vietnam study shows, 15 percent of veterans still suffered from PTSD, the most serious of trauma reactions.

http://www.informationclearinghouse.info/article3030.htm

It doesn't advance understanding merely to assert that all soldiers return not "normal" - especially when merely based on seeing some of them smile.  

Maybe it's because I'm a Londoner - that I moved to Nice.