Key drivers of change in defense technology in Southeast Asia are regional insecurities and, more recently, the rise of China. Most countries in the region harbor some animosities toward each other that, while not manifesting themselves in a full-blown arms race, at least contribute to an “arms competition” within the community. This results in “tit-for-tat” arms acquisitions inconsistent with mere modernization. China’s recent actions in the South China Sea add to the regional insecurities that seem to rationalize the qualitative arms buildup for the countries involved. While the number of advanced systems remains small, these upgrades have the potential to make conflict much more devastating should it occur.