Why do Western countries continue to spend on wars and such things despite their debts?

Okay so I am not really supporting any side, I am apolitical or neutral basically but this question has been making me wonder lately. So these days I can see that the west(Western nations like US, Germany, Greece, UK etc) have massive debts in trillions and their people stared to actually revolt against the cuts like in Greece and countries in the EU. Also since I live in America, I can see American people are pretty upset about the high unemployment and the bad economy. Anyways why are the Western countries continuing to get involved in wars and conflicts despite their debts? A good example of what I talking about is Greece, their economy is in really bad shape and their government decided to share in the Libya bombing thing. Why is that? It really makes no sense to me at all. Also US in that Libya revolution war thing.