Japan’s embassy in South Korea has begun posting data on its website to show there is little difference in radiation levels between the two countries in its latest retort in a diplomatic and trade row rooted in wartime history.South Korea said last month that it will double the radiation testing of some Japanese food exports due to potential contamination from the tsunami-damaged Fukushima nuclear plant.Explained: the legacy of war in AsiaThe embassy said the radiation reading in Seoul as of…