Of course there should be Hakaras Hatov to the IDF soldiers. A response to a small minority who think otherwise. Does Torah-learning fully protect us, or is an army necessary?

Is Hakaras Hatov a halachic requirement, or just a nice thing to do?
Do we just feel gratitude, or do we need to say “thank you” or more?
Historically, did the Gedolim show Hakaras Hatov towards the soldiers of the IDF?
Why have a few Roshei Yeshiva said they are concerned about showing gratitude?
If Torah learning protects, why does Israel need an army?
Does the Israeli army enable those in Yeshiva to learn? Do those learning in Yeshiva enable the army to have military success?