His latest tour of Jangjae Island and Mu Island was less dramatic than his last visit during soaring military tensions in March, when he threatened to "wipe out" the nearby South Korean island of Baengnyeong
Kim inspected newly built barracks, military positions and homes for soldiers and their families, the North's Korean Central News Agency (KCNA) said.
He also received a detailed report on "enemy positions" and "targets" on the equally fortified South Korean islands across the border.
In 2010, a South Korean naval vessel, the Cheonan, was sunk in the area with the loss of 46 lives, and later that year North Korea shelled the island of Yeonpyeong, killing four people.
The mood on the Korean peninsula has improved in recent months as the two Koreas have taken tentative steps to revive a number of suspended cross-border projects, but tensions remain.
On Friday, North Korea cancelled a visit by a US envoy, citing its anger over a recent South Korea-US joint military exercise.