The question isn’t really about the defensibility of borders anymore. Syria and Lebanon will never be strong enough to send an army to Israel, Egypt and Jordan are at peace with Israel, and any other country is far enough away that Israel would have time to prepare. The problem would be a potential Palestinian state, but as it stands there’s little to no chance of a functional Palestinian state with an organized military capable of invading Israel from happening. The real question is security against terror.
The question isn’t really about the defensibility of borders anymore. Syria and Lebanon will never be strong enough to send an army to Israel, Egypt and Jordan are at peace with Israel, and any other country is far enough away that Israel would have time to prepare. The problem would be a potential Palestinian state, but as it stands there’s little to no chance of a functional Palestinian state with an organized military capable of invading Israel from happening. The real question is security against terror.