Isn't a war of self-defense permissible and obligatory because of the ruling "Habah Lehargecha Hashkeim Lehargo"? When someone is coming to kill you, you kill him first.
In the case of Arabs attacking the state of Israel to get its land, the first law is certainly not pertinent. The Israelis could just hand over the land and surrender without a fight, and there would be no self-defense. However, one could argue that the second law permits them to kill the Arabs as thieves.
The fallacy here is that the Israelis are actually the original thieves. They stole the land from the Arabs and now, when the Arabs come to take it back, they have no right to kill them in defense of "their" property - it isn't really their property.
It is true that many Jews legitimately own land in Eretz Yisroel. But we are not discussing private land ownership now; we are discussing sovereignty. The Arabs wish to achieve sovereignty over the Holy Land, and then Jews who legitimately purchased their land can continue to own that land under the Arab government. They are not coming to take away private ownership from the Israelis; they are coming to take away sovereignty - sovereignty that was originally stolen by the Israelis.