Attack submarines (SSKs) are hot items on the shopping lists of several nations in southeast Asia: Malaysia, Singapore, Indonesia, Vietnam, Thailand, and the Philippines. See this article in the Jakarta Post.
As the author points out, an SSK's only purposes are military. If all of these nations buy and operate SSKs in these relatively limited and busy waters, incidents leading to regional war may well occur. Hat tip to RealClearWorld for the link.
