Possession is 9/10th of the law, and in this case, 9/10th of morality as well.
Those who seek a change in the status quo have the burden of coming forward and showing a willingness to negotiate.
It would be as if there was a dispute over a car, or a painting, or a piece of land. The person who was lawfully in possession of the item need do nothing unless the person seeking it offers to negotiate. If the claimant walks away from the negotiation, the status quo remains.
Of course captured land is not the same as a car or a painting, but the principles underlying negotiation are similar. The land at issue was never part of a Palestinian state. It was lawfully captured from Jordan in a defensive war.