This paper provides a political analysis on two territorial disputes that South Korea has with Japan over Dokdo/Takeshima and with China over Iŏdo/Suyan Rocks, as well as on their implications for the Northeast Asia region, focusing on the roles of sub-state actors and the United States as a third party trans-national actor. It mainly explores why South Koreans consider territorial claims by Japan and China such an affront as to require strident demonstration of ownership, especially since they already exercise effective control over the territories under dispute. It also explores what actions the South Korean government would take in the event of maneuvers or attempted landings by security forces or nationalists/fishing boats from China on Iŏdo or Japan on Dokdo. Employing Robert Putnam's Two Level Game Framework, the paper provides comparative insights on how these cases have been developed to date through interactions between Level I, official negotiators, and Level II, sub- and trans-national actors. The two cases demonstrate that the state is not a unified actor, and non-state actors' nationalistic collective sentiment has played (and will play) a greater role in shaping the directions of (potential) conflicts over Dokdo and Iŏdo.