"must" for necessity or certainty

[yunyun]

Excuse me, is must in the following sentence used to express what is necessary or what is certain:
"If I carry my gun and I am attacked, I must use it to kill, not just injure."
Thank u

[Tdol]

It's a strange sentence to me. What's the context? It would depend on the person and their reason for carrying a gun.

[yunyun]

The context is like this:
The speaker is an advocate of gun control, yet she keeps a gun by her bed. But she doesn't carry the gun to her car. She says, "I should transport the gun from my residence to my vehicle, but I don't. What the gun is capable of, what it is intended for, still frightens me more than what it may prevent. If I carry my gun and I am attacked, I must use it to kill, not just injure."
Thank U

[Tdol]

It sounds like an obligation- 'I would have to'. It's still a strange sentence because I see no reason why a gun cannot be used to injure rather than kill.