MOSCOW/KYIV, July 16 (Reuters) - Ukraine and Russia launched missile and drone attacks on Thursday on vessels in the Black Sea and the Sea of Azov, stepping up hostilities in a zone vital for grain exports that have triggered a rise in global wheat prices.

Ukraine fired more than 400 drones toward Moscow in its latest major attack on the Russian capital, the city’s mayor said Monday. The blitz came hours after Russia bombarded Kyiv and other Ukrainian cities with ballistic missiles in a relentless cycle of tit-for-tat strikes that make a settlement to end Moscow’s more than 4-year-old all-out invasion appear a distant possibility.

Ukrainian drone strikes on warehouses belonging to Wildberries, Russia’s largest online retailer, killed at least eight people and injured dozens Saturday.