The worst North Korean drought since 2001 has severely damaged staple crop production and could lead to serious food shortages, according to a new report from the U.N. Food and Agriculture Organization (FAO).

The FOA report, an early warning alert published Thursday, warns that a drop in bilateral food aid to North Korea — in part a result of sanctions imposed in response to the hermetic nation’s nuclear weapons program — has made the country especially vulnerable to famine.

Prolonged dry weather during the crucial period from April to late June is likely to cause a significant decrease in this year’s harvest, the report said. North Korea now requires “immediate interventions” such as food imports and agricultural assistance to make up for the shortfall.

“Seasonal rainfall in main cereal producing areas have been below the level of 2001, when cereal production dropped to the unprecedented level of only two million tonnes, causing a sharp deterioration in food security conditions of a large part of the population,” said Vincent Martin, an FAO representative in China and North Korea, in a press release that accompanied the report.

Read More: North Korea Tells Citizens to Prepare Themselves for Famine

Staple crops such as rice, maize, potatoes and soybean — which many North Koreans traditionally rely on to get through the May to September lean season — had been decimated by the drought. Vulnerable people such as children and the elderly would be worst affected by food insecurity, the FAO said.

Hundreds of thousands of North Koreans are believed to have died during widespread famine in the 1990’s.

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Write to Joseph Hincks at joseph.hincks@time.com.