In the Bhagavad-gita the necessity of killing during times of war that Krishna describes to Arjuna in his time of crisis, was just allowed and of concern to the Kshatriya caste of warriors and military elite of which Arjuna was one and not to the masses as a whole.
"Arjuna's dilemma" was to do with his not wanting to fight and kill on the battlefield relatives and friends that he grew up with and loved, Krishna explained to him that as a member of the warrior class he must fight as it was part and parcel of a Kshatriya's duty.