Yes! To me I feel as a security personnel, self defense is very necessary. Because without self-defence, you are likely exposed to dangers.
As a security personal, always being on guard is a must because the streets are dangerous. Going by the teachings, what if you kill while defending yourself? The teacher makes us to understand that such a person is not considered as a murderer because it wasn't intentional, it was out of defense. And on a normal, the killer wouldn't do that.
You might be thinking, " is it that, when once someone threateneds your life yiu should kill him or her before he or she kills you?" The answer here would be no! According to our teacher, he says, if you could do something that would stop or weaken him from proceeding on his or plans. Like if you were a personal, what you should do here is to be smart enough and accurate to shoot the thief either on the leg, or any place that would weaken and stop him from proceeding.
I think the teaching is very clear from the man of God.