Kyodo: The chief of the U.N. Environment Program urged Japan to keep playing a leadership role in the fight against global warming, although it faces a challenge caused by Fukushima nuclear disaster, which left most of its atomic plants offline. The world has in a sense believed in Japan as a leader and a pioneer. That is a brand many would like Japan to retain, UNEP Executive Director Achim Steiner said in an interview. There has been a tremendous disaster. That is very challenging for any country...