On Sunday, Azerbaijan began shelling Armenian positions in Nagorno-Karabakh — a disputed piece of territory in the Caucasus peopled primarily by the Armenians but owned, at least on paper, by Azerbaijan. In the 1920s, Soviet administrators, disregarding demography, had placed Nagorno-Karabakh inside Azerbaijan. In the run-up the USSR’s demise, the local Armenians voted overwhelmingly to secede from Azerbaijan in a referendum and proclaimed independence. Nobody recognised the result. And when the USSR collapsed, the place ended up inside the internationally recognised borders of Azerbaijan. A terrible war ensued. Armenia seized Nagorno-Karabakh and adjacent lands, Russia brokered a ceasefire, and an international forum called the Minsk Group was convened in 1992 to prod the two parties to settle their differences without spilling blood.