Haaretz has a disturbing story on the moral erosion in the fashion of young soldiers and delves into the psychology that inspires such imagery.
A particular quote that I feel sums up the complexity of the matter, especially considering many of these young people are barely adults making life and death decisions, was this:

“As a sniper, you get a lot of extreme situations. You suddenly see a small boy who picks up a weapon and it’s up to you to decide whether to shoot. These shirts are half-facetious, bordering on the truth, and they reflect the extreme situations you might encounter. The one who-honest-to-God sees the target with his own eyes – that’s the sniper.”

Now I’ve never been a soldier, and I do not desire to be. So I do not know what decision making like that entails, but I’ll tell you what I do know… slogans like “We came, we saw, we destroyed!” – alongside images of weapons, an angry soldier and a Palestinian village with a ruined mosque in the center or like “If you believe it can be fixed, then believe it can be destroyed!” well, I know those are just plain gross.
I understand that these things are “half-facetious” but they’re still half serious! Serious or not, humor like this says something quite loud about the culture that produces it. This reflects belligerence and racism in the worst regard. I do not know Israel well enough to know if this is truly indicative of its culture, but I do know Judaism, and to the Jewish culture that I know this just doesn’t seem okay.