The South Korean public, driven by fears over mad cow disease, has protested the deal in major cities, filed lawsuits to stop the deal and driven down the approval rating of the country’s president, elected only months ago in a landslide.

South Korea was once one of the largest overseas markets for American beef until bovine spongiform encephalopathy, also known as mad cow disease, was found in a cow in Washington state in 2003. Mad cow disease has been linked to variant Creutzfeldt-Jakob disease (vCJD), a similar disease in humans. In both illnesses, the infectious agent attacks the central nervous system.