Cruelty for the sake of forging

In many armies, it is common for training to be characterized by a bad attitude toward recruits with the intention of strengthening their resilience and accustoming them to discipline. My question is, is it moral to harm a person in order to benefit him (to strengthen him)? And is it moral to harm a soldier in order to benefit the country in the same way?
It seems that many people would rule out the first option and justify the second. Perhaps because in the army it is a long training process that can be ensured will indeed lead to good results, or because military service is seen as a necessity of the state and an obligation on the soldier.