Japanese Education Minister Hakubun Shimomura announced on Tuesday that the ministry has revised the teaching manuals for junior and senior high schools to claim territories in dispute between Japan and China and between Japan and South Korea. The new teaching manuals describe the disputed territories as "Japan's integral parts," according to Japan's Kyodo News agency. It is unusual to revise the manuals now as they are usually revised every 10 years along with the amendment of curriculum guidelines, said Kyodo, adding the existing teaching manuals for junior and senior high schools were published in 2008 and 2009 respectively. Textbook revision is to blame for strained ties between Japan and its neighboring countries as the issue reflects Japan's attitude toward its militarist past.