As the UN tries to broker a path for grain from Ukraine and temper worries about a global food crisis, hundreds of mines laid along the Black Sea present a practical nightmare that would take months to resolve even after any agreement. The Black Sea is crucial for shipment of grain, oil and oil products. Its waters are shared by Bulgaria, Romania, Georgia and Turkey, as well as Ukraine and Russia. Ukrainian government officials estimate 20 million tonnes of grain are unable to travel from what was the world’s fourth-largest exporter prior to the Russian invasion on Feb. 24. Kyiv and Western ...