system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do global rules of war work? How does one enforce the rules while at war with another country? What would stop an opposing power from breaking these rules?
gpt
If you break the rules, you will be sanctioned. This makes it a lot harder to access the global market, making you poorer and less able to fight the war. If you lose the war then you may be tried in a court for war crimes and imprisoned.

Alternatively, the enemy may start to commit war crimes against you and your soldiers become scared and demoralized and become a less effective fighting force.