By Pavel Polityuk, Max Hunder and Michelle Nichols KYIV/UNITED NATIONS (Reuters) -The first shipments of Ukrainian grain could leave Black Sea ports within days under a U.N.-brokered deal to tackle a global food crisis that has worsened since Russia invaded its neighbor, the United Nations and Ukraine said on Monday. “All parties have reconfirmed their commitment,” said deputy U.N. spokesperson Farhan Haq after a Russian missile strike on Ukraine’s Odesa port on Saturday cast doubt on the one-day old deal Moscow agreed with Ukraine, Turkey and the United Nations. The agreement aims to allow sa…