That book was set in communist China. Their perpetual war was a war of occupation in "Oceanea" or whatever they called it, which I suspect was the continent currently known as north america, however the book is set well after the engineered collapse of the united States making it more like the middle east with lots of little shithole states fighting with each other constantly while China plays the role of the US periodically bombing a wedding or a hospital with their drones and mostly sending troops here to guard the opium fields or to traffic in abducted Christian children.