as for the land “being given to us” – what happened the day the state was declared? arab armies swarmed EY. they clearly didnt want to give it to us. And the UN’s decision hadn’t been implemented; it was still pending when the zionists made trheir declaration of a shmad state.
And who says that the UN are baalei batim over the whole world? The arabs were opposed; thats enough to no longer conisder it “permission”
one of the oaths is not to fight goyim, too, which would mean it’s better for us to flee EY if we’re under attack than to fight.
In practice, however, many poskiim allow fighting nowadays for self defense, for a variety of reasons; while it might be better to run away, how would we take millions of jews, including elderly, babies, etc…? it would be pikuach nefesh.