This is under Article 7 of the Hamas Covenant of 1988. The section is titled "
The Universality of the Islamic Resistance Movement"
Also, this under Article 11:
This is what the Palestinian populace voted for.
As I said, the Jewish side isn't without its religious extremism as well. Torah calls from them to remove every non-jew inhabitant of the land. The fact that they didn't do it the first time is the reason why they're in the situation they're in now. Consequences they have to deal with.
So you have Zionism and Sharia battling for dominance. Let them be.