One of the main challenges of maintaining peaceful international relations is the escalation of distrust and the ensuing arms race.
The possibility that others might attack you is a reason to arm yourself. But this step will in turn be interpreted as a threat by the other, who will in turn arm itself (even more). Etc.
Aren’t there ways to simply invest in purely defensive weapons? So that your efforts to remain safe do not in turn threaten others? Which in turn allows others to also de-escalate?
In other words, are there military set-ups that are useless for offensive actions but good enough for defending a country?
“Defence only” gives an attacking side 100% initiative and control over what’s going on. They can focus on one place, attack when you are the weakest, take control of that one place (city, village or even a building) and even if it costs them a lot, you have no way to punish it. They can take their time to recover and wait and attack again whenever they want.