Demonstrations initially against tax reform have bloomed—and turned violent. The reforms have been shelved, but the protests now threaten President Iván Duque’s rule. The emissions contributions of the world’s armed forces are rarely reported and largely overlooked; we examine the efforts to make armies a bit greener. And an audio tour through popular music’s accidental innovators. For full access to print, digital and audio editions of The Economist, subscribe here www.economist.com/intelligenceoffer