The United States has suspended the purchase of food aid for North Korea because of uncertainty over the U.N. organization overseeing distribution there.

The U.S. State Department on Thursday said it has not purchased the 25,000 tons slated for shipping later this month due to uncertainty whether the World Food Program is still running in the North and can monitor distribution.

Washington has shipped half of its pledge of 50,000 tons of food to the World Food Program.

The U.S. Agency for International Development had announced early last month that it cannot ship food aid to the North if the WFP is forced out of the country.