Goma, the largest city in the east of the Democratic Republic of Congo, fell to M23, an armed group backed by Rwanda. The capture of Goma marks a stunning escalation of hostilities between Paul Kagame, Rwanda’s president, and his country’s much larger neighbour. African and Western diplomats have roundly condemned the attack but are unlikely to force Mr Kagame to reverse course. The incursion raises the risk of a wider conflict in the region, which suffered two devastating wars between 1996 and 2003.