ODESA, Ukraine -- Russia's invasion of Ukraine has meant vital food exports are stuck in Ukraine's ports.
ABC News foreign correspondent Tom Soufi Burridge explains a looming crisis by answering four key questions.
1. How important is Ukraine's food production for the world?
Ukraine is a vast agricultural production house.
The country produces 46% of the world's sunflower oil exports, 37% of global millet (a small grain cereal) exports, 13% of all barley exports, 10% of total wheat exports, 8% of honey and 7% of walnut exports, according to the Ukrainian Agribusiness Club.
Before Russia invaded, most of Ukraine's food production was exported through the country's Black Sea ports.
Earlier this month, the United Nations World Food Programme said those exports would normally feed 400 million people around the world.
The Middle East and Africa are Ukraine's main food export markets, said Professor Oleg Nivievskyi from Kyiv's School of Economics.
By gaining rare access inside a grain terminal in Odesa's port, ABC News was able to witness the vast infrastructure that would normally be used to ship the produce out.
Pre-war, the terminal would receive a hundred truck loads and a hundred train wagons of grain in a single day, said Oleksandr Guzenko, the plant's chief engineer.
In a single hour, 400 tons of grain would normally flow through the plant and out to ships waiting in the dock, Guzenko added.
However, these are abnormal times.
2. What is the impact of the Russia's blockade of the Black Sea?
The grain terminal at the Port of Odesa is depressingly idle and silent.
Chief Engineer Oleksandr Guzenko told ABC News he felt "helpless."
The Russian threat at sea means there is no safe route for commercial vessels to exit and vast quantities of food exports are stuck in Ukraine's Black Sea ports.
It is becoming "a disaster" for Ukrainian farmers.
"If the ports don't open soon, we are stuck with the crops," said Kees Huizinga, who owns a 40,000-acre farm in Kyshchentsi in the Cherkasy region, south of Kyiv.
His business would gradually run out of money, he told ABC News, and planting for next year's harvest is already at risk.
Huizinga predicted the world's food supply could be "disrupted for the coming decade" if the situation isn't solved soon.
However, the blockade is having a ripple effect far beyond Ukraine.
The U.N.'s World Food Programme said global food prices have risen sharply since Russia launched its full-scale invasion of Ukraine and vulnerable communities in parts of East Africa are at risk.
Even before Russia attacked Ukraine, the WFP was forecasting a year of "catastrophic hunger," because global resources were not keeping pace with demand.
In the first month of the war, export prices for wheat and maize rose by 22% and 20%, respectively, "on top of steep rises in 2021," according to the WFP.
WFP Executive Director David Beasley told ABC News the war is a "catastrophe on top of a catastrophe."
"The world demands [that the ports open], because hundreds of millions of people globally depend on food that comes through these ports," Beasley said.
3. What is causing the blockade?
Russian President Vladimir Putin and his generals have spoken openly about their desire to capture Ukraine's largest port, Odesa, and possibly the entire Ukrainian coastline -- which would throttle Ukraine's economy.
When Russia invaded Ukraine in late February, there was a possibility that the Russian navy might launch an assault on Ukraine's southwestern coast from the sea.
By capturing Snake Island, a strategically important slice of dry land off Ukraine's western coast, on day one of the war, the Kremlin signaled its intent.
In response to the Russian threat, Ukraine quickly placed mines in the Black Sea near Odesa and other major ports.
In a briefing with ABC News this week, a NATO official said coastal defenses were necessary "in order to deter or thwart a potential Russian amphibious landing."
The Russian government recently said it was ready to provide a humanitarian corridor for ships carrying food, in return for the lifting of Western sanctions. It called on Ukraine to de-mine the Black Sea.
However, the U.K. Ministry of Defense accused Russia of "introducing an alternative narrative" to complicate people's understanding of the original cause of the blockade.
Ukraine has only deployed maritime mines, the U.K.'s Ministry of Defense said, "because of the continued credible threat of Russian amphibious assaults from the Black Sea."
4. Why do Western leaders accuse Putin of "weaponizing hunger" and is there a solution on the horizon?
U.S. Secretary of State Antony Blinken recently accused Putin of "using food as a weapon."
The Biden administration and its Western allies make this accusation because Russia's invasion of Ukraine was unprovoked and the Kremlin has the ability to drop its threat on ports such as Odesa.
"If Kyiv solves the problem of de-mining ports, then the Russian navy will ensure unhindered passage of ships with grain to the Mediterranean Sea," Russian Foreign Minister Sergey Lavrov responded on Tuesday to international criticism.
The White House has already ruled out meeting Russia's demand to drop sanctions in return for an end to the blockade.
What military guarantees Russia could offer Ukraine, in order for Ukraine to demine the Black Sea, is not at all clear.
A senior NATO official offered a blunt assessment to ABC News in the context of Tuesday's back and forth: Ukraine cannot trust anything Russia says.
That said, European countries, namely France and Germany, are negotiating the issue with Russia.
In the meantime, Ukraine and the European Union are trying to increase Ukrainian food exports by road and rail.
However, Nivievskyi, from Kyiv's School of Economics, warned it is "not physically possible" to transport the huge amount of grain by rail and road.
By his calculation, rail and road routes have only about 10% of the export capacity of Ukraine's Black Sea ports.