Before Russia invaded the country, Ukraine was one of the primary providers of several staple crops to world markets, including corn, wheat, maize, and barley. Agricultural products were Ukraine’s primary source of export revenue and accounted for nearly 10% of the country’s GDP.

But the war and blockades of Ukrainian port cities have halted global supply chains for these food products. And the UN’s hunger and food security organization is warning that a food crisis beckons if that remains the case.

“In 2023, you will have a food shortage problem,” David Beasley, executive director of the UN’s World Food Programme, said at a conference on Thursday.  

Around 25 million tons of various staple grains are currently sitting in storage units in large port cities such as Odesa, waiting to be shipped to international markets, but they are unable to leave Ukraine because of an ongoing Russian blockade in the Black Sea.

On a recent visit to Odesa, the president of the European Council, Charles Michel, tweeted that he saw “silos full of grain, wheat and corn ready for export. This badly needed food is stranded because of the Russian war and blockade of Black Sea ports.”

On Thursday, Beasley implored Russian officials to lift the blockade at all costs to avert a global food shortage.

“If you have any heart at all for the rest of the world, regardless of how you feel about Ukraine, you need to open up those ports,” he told CNN in statements directed at Russian President Vladimir Putin.

An indefinite blockade of Ukrainian ports would affect every country in the world, but some are more in need of food imports than others, and more at risk of a catastrophic food shortage.

Speaking at the Munich Security Conference on Friday, Beasley warned that several countries in North and East Africa and the Middle East were poised to face “tremendous food security issues” in the near future due to the Ukraine war. 

Several countries—including Tanzania, Uganda, Sudan, and Cameroon—relied on Ukraine and Russia for at least half of their wheat imports before the war, according to the international NGO Human Rights Watch. Should food products remain stuck in Ukraine, these countries will be hit by food shortages first and hardest. 

Beasley also warned that missing food exports from Ukraine are adding to preexisting food insecurity affecting the world’s more vulnerable regions this year, including the pandemic, severe weather events, and droughts hurting harvests.

Should the looming food shortage issues fail to be addressed, Beasley warned that it could lead to a “crisis on top of a crisis, a tsunami within a tsunami. And that, we can’t afford right now.”