Almost 10 million metric tons of Ukrainian grain has been affected by the Russian invasion, according to a new analysis of satellite imagery. One in six of Ukraine’s grain storage facilities— which have a total capacity of 58 million metric tons—have been impacted by the conflict, either through damage, destruction, or falling under Russia’s control.

The Conflict Observatory, the organization that conducted the analysis, found substantial evidence of damage to grain silos from either indiscriminate or targeted bombardment. And as the conflict rolls on, concerns are being raised about crops that need planting now. “If Ukraine does not have enough storage capacity, farmers may not plant a winter wheat crop,” says Nathaniel Raymond, a coleader of the Humanitarian Research Lab and lecturer at Yale’s School of Public Health who led the project. “If they can’t store the upcoming harvest, it’ll be a crisis of availability.”

In order to get a true sense of the damage caused to Ukraine’s grain storage facilities, the Conflict Observatory, in partnership with the US Department of Energy’s Oak Ridge National Laboratory, built an object detection algorithm that was able to analyze commercial satellite imagery to find previously unidentified silos that had sustained damage during the conflict. The team used historical satellite images as well as images of storage facilities known to have sustained damage to train the algorithm to find other facilities that had also been impacted. The research focused on particular areas that were within range of known missile bombardments. From there, the researchers were able to estimate approximately how much grain had been destroyed.

Though the researchers were not able to analyze every facility—the country has about 1,300 grain silos, of which the report examined 344—it is the largest assessment to date.

“There have been efforts to estimate the damage to grain storage capacity in Ukraine because of its clear and present danger to the global food supply,” says Raymond. “The amount of grain that can be stored in these facilities that we looked at represents almost a quarter of Ukraine’s grain supply.”

For months after its invasion, Russia blocked grain exports from Ukraine, threatening to create a global food crisis. “For people around the world, the war, together with the other crises, is threatening to unleash an unprecedented wave of hunger and destitution, leaving social and economic chaos in its wake,” UN Secretary General António Guterres said in June. At the end of July, Russia agreed to allow some shipments of the 20 million tons of grain and other foods that had been held up in the country from certain Ukrainian ports. Though global food prices have begun to drop in response, Russian president Vladimir Putin has since threatened to end the deal.

The need for stable grain storage infrastructure in Ukraine is acute. Grains and other crops often need to be stored in very specific conditions in order to avoid spoiling. Any variation in factors such as temperature or moisture can drastically cut down on the length of time the crops stay good. According to the report, even if a storage structure appears to be mostly intact, even minor damage can make crops go bad.

“In the case of, say, hospitals or schools that we’ve looked at in previous reports, those facilities can actually sometimes withstand more damage than a grain silo, which is aluminum, which is fragile,” says Raymond.

The damage done to Ukraine’s grain supply, in addition to the effects of the Russian blockade, has particularly damning implications for countries in the Global South, where Ukrainian wheat comprises a substantial portion of grain imports. Countries like Egypt, Indonesia, Bangladesh, and Yemen all rely heavily on Ukrainian grain. About 40 percent of the World Food Programme’s emergency wheat supply comes from Ukraine.

And while it is unclear whether grain storage facilities were specifically targeted by Russian forces, or suffered from collateral damage of other strikes (most of the damaged facilities were near transportation infrastructure), Matthew Steinhelfer, deputy assistant secretary at the US State Department, says that attacking the country’s food and agriculture infrastructure could violate international law.

“Not only is Russia exacerbating the global security crisis, but this unjustified war and their attacks on these facilities—destroying, damaging, and degrading to the point of compromising the stocks and potentially any future ability to continue to store in those silos—is a great concern,” Steinhelfer says. “Intentional destruction of these facilities may constitute a war crime.”

Satellite imagery has featured prominently in the war in Ukraine. The Conflict Observatory previously used open source images and satellite imagery to identify filtration camps in Ukraine.

Steinhelfer hopes the report informs conversations at the upcoming UN General Assembly. “Whether these attacks were indiscriminate or intentional, the legal status of this behavior is the same,” says Raymond. “A systematic attack on a country’s ability to produce and store food can constitute a clear war crime. Full stop.”