The modernisation of the Republic of Korea Navy from the election of Kim, Young-sam in 1993 to the sinking of the Cheonan has been remarkable in that it is a microcosm of the security dilemma that the ROK faces; how to deal with the threat from the DPRK while developing a defence capability that is commensurate with a middle power with global interests. This thesis examines said modernisation both through an analysis of the force development program and its driving factors. Its original contribution is in its use of previously unavailable sources and author conducted interviews to demonstrate for the first time that ROKN modernisation in its nature, drivers and hindrances is a synthesis of a multitude of factors both internal and external. While much focus has been on the developing regional capability that the ROKN has pursued, this thesis demonstrates that regional capability is part of a wider force improvement program which encompasses C4ISR, strike and power projection capabilities aimed at meeting all of the threats both current and future that the ROK perceives. What has driven such modernisation is a focal point of the thesis, demonstrating that while the East Asian maritime security environment and the development of the Korean People's Navy has played an important role, the decision to construct a more powerful navy is ultimately an expression of the ROK's political and economic development. This thesis concludes however with the caveat that force modernisation is ultimately dependent on political support and incidents such as the sinking of the Cheonan have a large bearing on the nature and extent of naval modernisation.