First and foremost, I would like to thank Prof. Irmgard Marboe, without whose support I would never have found my way into the world of international law. This book was also made possible by Prof. Dai Tamada and Prof. Shotaro Hamamoto of Kyoto University. I was very fortunate to be able to spend six weeks in the very stimulating environment of Kyoto University to conduct my research. At Osaka University, I would like to thank Prof. Akira Mayama for giving me the opportunity to visit the National Institute of Defence Studies in Tokyo.