Russia's assault on Ukraine has had global economic consequences. The world's food supply chain has been severely disrupted by port closures and a trading halt due to Russian blockades. Major ports of Ukraine have been blocked since the February 24 invasion. It has resulted in added volatility in global financial markets. Commodity prices have spiked after the conflict broke out, according to reports from Reuters. Also Read:UK schoolboy's 'best president' letter brings 'smile' to Zelensky's face Ukraine has been the source of multiple crucial crops consumed all across the world -- including wheat and maize. According to data from the International Grains Council, Kyiv was the fourth-largest exporter of wheat and the sixth largest of corn in 2020-2021. However, authorities have majorly shifted focus with the Russian invasion, according to a report from Reuters. About 25 million tonnes of grains are now stuck in Ukraine. Ukraine's agricultural authorities have said that the country has such large reserves currently that there may not be enough room to store the harvest. In a recent video address, Ukrainian President Volodymyr Zelensky said, For the first time in decades and decades, in Odesa, there is no regular movement of the merchant fleet, there is no routine port work. This has probably never happened in Odesa since World War Two. Also Read:Russia's Bastion missiles in Ukraine: All you need to know The Mariupol and Odesa factor Russian forces have taken over the crucial port city of Mariupol from Ukraine, cutting off Kyiv's control from the trade point. Moreover, media reports suggest that Odesa may be the new target as Moscow's forces travel north. If taken over, the isolation of Odesa ports may further hamper Ukraine's participation in trading grains. Being the largest port in the Black Sea basin, Odesa reportedly hasa total annual traffic capacity of 40 million tonnes. It is also directly connected to Ukraine's railway routes.