I recall an old Science Fiction story along the same lines, back in the early 80s.
The protagonist was a young man in a third-world middle-eastern shitehole. He was tired of war, of losing friends and families, when he had a revelation: the "Blue Hats" (UN) were neutral, so if he joined their "army" he'd be relatively safe and wouldn't have to fight any more.
So, he obtains a discarded steel pot and paints it blue. Reveling in his newfound "immunity," he convinces his friends and neighbors to do the same. Even the other side starts doing it until everyone is a Blue Hat -- and peace breaks out for the first time in living memory.
I forget how it ended, but the gist was that the First-World was using the Third-World as a "live culture" of warfare, to keep the former's own troops trained and budgets justified. The old sides were eventually convinced to go back to fighting one another.