Japan initially banned American beef in December 2003 following the first discovery of mad cow disease in the U.S. This ban was eased last December to allow the importation of meat from cows aged 20 months or less, seen as posing a lower risk of having the disease. The country banned U.S. beef again in January after a shipment violated a prohibition on bones, which Tokyo considers a mad cow disease risk.
The mad cow scares have greatly eroded the popularity of American beef in Japan, once the most lucrative overseas market for the U.S. meat.