It would be nice if humans could find ways to not kill each other, but the reality is humans have a very poor track record and you would be a fool to not put at least some effort into defending yourself.
Rich free market democracies don't fight wars against each other.
Economic warfare also does in fact kill people. Denying a population, e. g., Cuba, the ability to access medicine/food kills humans just as well as a bullet in the long term.
There are various other ways this causes suffering. Different forms of warfare are still warfare, even if you don't to hold a gun for all of them.
Being "rich" also requires someone else to be "poor".
Market democracy is not perfect but it solves 90% of the problems we'd have otherwise.
Deny them jobs, investment that could create jobs and paths to prosperity.
Give them drugs.
Shocked Pikachu when they don't like you.
Edit: Revised language to be more broadly applicable.
- NATO v Yugoslavia 1999 - India v Pakistan 1999 - Russia v Georgia 2008 - Russia v Ukraine 2014, 2022
The greatest failure of the past 20 years was the belief that if we open up trade and grow rich together, rational self-interest will lead to liberalization and peace. Instead, it just gave our enemies more resources to spend on self-destructive imperialist ambitions.
But it turns out that when a fascist has nukes, there's not much you can do to convince them to not be fascist.