While the war in Ukraine has dramatically affected global wheat supplies, its food security implications vary substantially across countries, depending on their vulnerability to supply disruptions and ability to access food reserves. New trade data obtained after the onset of the conflict reveal a 75% decrease in wheat export from Ukraine, with the potential to push average calorie intakes below malnutrition thresholds in the most vulnerable countries. Differences in access to international trade determine the impact of supply disruptions and suggest the need for policy measures to defuse the impending food crisis.