Safety first

We spend hundreds of billions of dollars every year in the name of security, with soldiers stationed in 150 countries around the world.  We have also spent 6,440 lives in the past decade toward this goal.  We have been involved in (by my count) 9 major foreign wars since 1815, in which time Switzerland has been involved in exactly 0.  Instead of spending money of aircraft carriers and nuclear weapons, they devote their defense resources to nuclear shelters and the ability to turn their country into a fortress.  They have their bridges and tunnels wired to be destroyed in the event of invasion, and much of their populace is trained and armed for military combat.

But in 200 years, they haven't had to use these capabilities.  On the one hand, the tremendous defense capabilities of the Swiss makes them an unappealing target for potential invaders.   More importantly, their strong traditions of neutrality and non-aggression have successfully kept anyone from really wanting to invade them in the first place.

These two factors are related.  If your people are confident they will never be taken over and make that security real by giving them a weapon and plenty of access to fallout shelters, it's tough to get them riled up enough to attack someone else.  And it's hard to find people willing to launch terrorist attacks on a neutral nation.

It is sometimes claimed that our economic position in the world would be endangered if we took a more isolationist approach to our military endeavors.  Switzerland's almost-identical record on GDP per capita puts that argument to bed.

We are currently killing people in several countries and creating new enemies every time we do it, whether or not those killed needed to be for some objective reason.  We wind up more fearful and less secure than we would be if the Department of Defense used its massive budget for actual defense.