Ukraine fortifies its front lines in anticipation of new Russian offensive this summer

Though Russia has made no major gains on the Ukrainian front line since February, its forces are keeping up the pressure, with the avowed aim of seizing more territory. Last year, the Ukrainians found their attempts to liberate more of the occupied lands stymied by Russian-built fortifications. But, hoping for swift victories, they hadn’t really built an equivalent on their side. They’re now scrambling to do so before the Russians – who’ve just launched a major mobilisation drive – gather their strength for a summer offensive. FRANCE 24's correspondent in Ukraine Gulliver Cragg reports on one of the key challenges for Ukraine this year.