Look at it this way... they are an organisation (political party, actually) that lists the complete destruction of Israel in their goals. When they started to get funding and weapons from countries like Iran and Syria, and they were pissed at the Israelis, they started going missile on their asses.
Of course, it's a lot more complicated than that, but there's the gist of it. Yes, one COULD write a 1000 page essay on this, but let's not.