Expanded use of the Chinese currency beyond China’s own borders is an important indication of China’s growing influence in global affairs. Contrary to earlier expectations however, China has only internationalized its currency, the renminbi (RMB), on a very limited scale. While this outcome is not altogether puzzling, we argue that the conventional wisdom on international reserve currencies has overlooked security considerations, namely security and military partnerships from the currency issuing state, and the external security environment as key factors in generating and strengthening support for international markets in its currency. We advance an historically informed argument of the security limits to RMB internationalization. We demonstrate that the deployment of China’s primary tool for currency internationalization—RMB swaps—is constrained by the dual exigencies of guaranteeing security for overseas economic interests in addition to domestic goals of maintaining domestic financial stability. We then show that RMB internationalization is influenced by both Chinese and US security alliances. We find that, counterintuitively, the growth of China’s military power and ability to back its economic interest seem to constrain its choice of BSA partners in regions closer to China given existing US military alliances.