The surprise visit to Yeonpyeong was the first time Lee had set foot on the island near the Yellow Sea border with the North, Yonhap News Agency reported.
North Korea shelled the island in 2010, killing two soldiers and two civilians. Lee visited the island reportedly to check on military preparedness.
Yeonpyeong lies on the edge of a maritime boundary drawn unilaterally by the United Nations Command at the end of the Korean conflict in 1953. North Korea has never recognized the boundary and has demanded the line be redrawn further south.