Building an economy often takes decades of patient labour. Yet the collapse of political institutions, or the eruption of conflict in the aftermath of revolutions and coups, can cancel out years of growth with startling speed, condemning nations to a long and punishing struggle to recover what they have lost. Yemen offers a stark illustration of this reality. A Houthi takeover of Sana'a in September 2014 led to the outbreak of war in 2015, when a regional coalition intervened to support the internationally recognised government of Yemen.