South Korea’s security does not end at the border with North Korea. Crude oil and liquefied natural gas from the Middle East must cross distant seas and reach our ports to keep factories running and sustain everyday life. Merchant ships carrying Korean exports also travel the world’s shipping routes. Sea lanes are the lifelines of our economy. With world-class shipbuilding capabilities and extensive international trade, have we also secured sufficient capacity to protect those lifelines? South Korea’s defense posture has evolved primarily in response to the threat posed by North Korea’s ground forces. There were sound reasons for committing substantial resources to land defense, yet we must ask whether threats in distant waters and the importance of maritime security have received sufficient attention. Operational planning that places considerable weight on U.S. naval support has also contributed to an underestimation of the need for South Korea’s own oceangoing forces. The South Korea-U.S. alliance remains central to our security, but combined operations to defend the penins