Does that mean supporting the expulsion of millions of people?
I'd say it supports the repatriation of any number of enemy combatants from occupying a sovereign nation.
I hadn't brushed up on the Geneva conventions for quite a while but The UN charter gives member states the right of self defense. While the Geneva conventions dictates the treatment of prisoners of war as well as civilians. With the Arab leagues declaration of invasion/war. ( most declarations of war don't actually use the term war ) Israel is clearly and legally defending itself within the mandated area west of the Jordan river. All of the area west of the Jordan river as the area was never legally segregated into Judaic and Arab zones. So I think sovereignty reverts to its last legally agreed upon use.
In any case I'd say the law is clearly on the Israeli side in its response to any remaining hostile combatants against the state whether they be the original hostiles or the descendants of those original hostiles. The conventions require Israel to repatriate those hostiles at the cessation of hostilities
Which IMHO means the states that declared war against Israel. But it gets muddy. Its posible not all combatants to be expelled are from Egypt Jordan Syrian Iraq or Lebanon. Its also obvious that these signatories to the declaration of war might not allow their defeated armies to return.
Its really quite clear that Israel has not just a right but an obligation to repatriate prisoners of war. Really the only question that I don't have an answer to at the moment is where in the conventions a country is required to accept the return of its defeated armies.
Maybe Rocco has an answer to that one
But Israel under the conventions is allowed to detain combatants, anyone lending aid to combatants even anyone suspected of aiding or being a combatants and considering them prisoners of war.
The conventions also suggest after a period of one year after the end of hostilities prisoners of war should be returned. And it looks like there's no provision preventing the parol of prisoners during an ongoing conflict. So really Israel could unilaterally begin repatriation any time and simply hand the prisoners over to the red cross. Let them figure out who's going to take them.
In the end no more land should be offered by Israel to anyone and everything they presently have the international community should recognize as being annexed into Israel. I'd also fully support the repatriation of any hostile forces which remain in Israel either to their respective countries or to the red cross, without delay.