The effectiveness of these constraints must be understood against the backdrop of modern Japanese history and within the context of the conflicting systems of ideas that have shaped Japanese thinking about their role since 1945. The former inculcated the sense that, as an outsider and a late developer, Japan had to assess the international condition set by the great powers and respond to them so as to best advantage Japan. The latter set up a tension between the pattern of ideas associated with the so-called peace constitution, by which the Japanese were pledged to renounce war forever, and the ideas associated with the security alliance with the United States. Japanese leaders were forever seeking to balance the two.