Answer

Hello.
I also join in what your rabbi said:

With God’s help, 4 Adar 5778
 
 
To Mr. ___,
Peace and blessings.
 
 
I find it difficult to understand the discussion, and it seems to me that it is missing components.
I do not know of even a single halakhic decisor who maintains that if what is at stake is the very existence of the State of Israel versus handing over part of its territory to the enemy, one should refrain from handing over the territory, bring about the collapse of the State of Israel, and be conquered by the gentiles, or be removed from the Land.
Even Rabbi Avraham Shapira of blessed memory, who stood at the forefront of those opposing the surrender of parts of the Land of Israel, wrote this at the end of his famous article on the subject in the volumes of Techumin.
Like many questions in Jewish law, and like many topics in the Talmud, one must first go through a process of sharpening exactly what the question under discussion is, and then one can see the range of opinions regarding it.
 
 
                                                                                                            All the best
                                                                                                            and more power to you for the clarification
 

Beyond that, you need to define what counts as a risk. Many things we do involve risk on one level or another, and not everything of that sort is considered halakhically to be a danger. Even for an individual, a distinction is made between accepted risks, about which it is said “The Lord protects the simple,” and significant, non-accepted risks.
However, regarding war over the Land, the Minchat Chinuch already wrote that war itself is a risk, and that is certainly something we are obligated to undertake by virtue of the commandment of conquering the Land. So clearly danger to life does not exempt one from conquering the Land. But there we are speaking about risk to individual soldiers. A significant risk to the entire state overrides conquering the Land according to all opinions, even in a case of doubt. Why? Because in my view, a significant risk to a state has the status of its certain destruction, just as with an individual a possible life-threatening danger is treated as certain danger. See the passage in Yoma 85, where all the sources brought to show that danger to life overrides the Sabbath were rejected because they do not teach this regarding doubt, only regarding certainty. This shows that it was entirely obvious to the Talmud, even before the sources were brought, that the law of doubt is the same as that of certainty.
But by the same analogy, a small risk of the sort that states take can be taken here as well, although with regard to the public they were more stringent about the level of risks. But in my opinion this is a statistical question. See the article by my student Hanan Ariel in Tzohar many years ago about the obligation of public transportation.