Russia and Ukraine signed a landmark deal in Istanbul to reopen Ukrainian Black Sea ports for grain exports, raising hopes that an international food crisis aggravated by the Russian invasion can be eased. A blockade of Ukrainian ports by Russia's Black Sea fleet, trapping tens of millions of tonnes of grain in silos and stranding many ships, has worsened global supply chain bottlenecks and, along with sweeping Western sanctions, stoked galloping inflation in food and energy prices around the world. Watch this video for more.