Thousands of Indonesian firefighters are locked in an around-the-clock game of Whack-a-Mole as they battle to extinguish an invisible enemy, underground fires that aggravate global warming. Vast blazes are ripping across the archipelago’s rainforests, unleashing a toxic haze over Southeast Asia that has triggered health fears and sent diplomatic tensions with Indonesia’s neighbours soaring. Jakarta deployed more than 9,000 personnel to battle fires turning land into charred landscapes and consuming forests in hard-hit Sumatra and Borneo island. But many of the blazes smoulder deep underground in once-swampy areas known as peatlands, where they can last for months and release eye-watering amounts of thick, acrid smoke. “It’s so much harder to fight fires on peatlands,” a dirty and exhausted Hendri Kusnardi told AFP outside smog-hit Pekanbaru city in Sumatra.