It is Forbidden to Give Away Parts of the Land of Israel Because it Endangers Lives

It is dangerous to give back parts of the Land of Israel that G-d has given into our hands in our time. It endangers lives. We are required to desecrate Shabbos if non-Jews attack Jewish cities, and even if they didn’t attack yet but are preparing to attack. In a border city we must desecrate Shabbos to attack them even if they are only coming about “matters of straw and hay” because if they conquer the city it will be easy for them to conquer the land, G-d forbid.

(See talk of the Lubavitcher Rebbe King Moshiach Shlita, Bereishis 5752 (1991) and more)