President Moon Jae-in called for stepped up efforts to resume dialogue with North Korea on Tuesday, hours after the communist state launched a missile that flew over Japan in the latest violation of UN Security Council resolutions.

Moon made the remarks in a ceremony at the presidential office Cheong Wa Dae to appoint the new vice chairman of an advisory council on unification headed by the president himself.

"It is true the National Unification Advisory Council has not been able to show its presence as the inter-Korean relations came to a halt over the past 10 years," the president said, according to Cheong Wa Dae spokesman Park Soo-hyun.

"Even today, North Korea made a missile provocation, but that is when we must work harder to bring about a change in the South-North relations," Moon was quoted as saying.

North Korea launched what Seoul officials said appeared to be an intermediate range ballistic missile early Tuesday.

The projectile flew directly over Japan, marking the first such incident since 2009.

Earlier, the South Korean president ordered the country's military to stage a show of "overwhelming" force that can counter any additional North Korean provocations.

At the appointment ceremony that also involved the new head of the Northern Economic Cooperation Committee, Moon stressed the need to improve economic cooperation with the communist North.

"The Northern Economic Cooperation Committee is the first of its kind established by our government not only for economic cooperation with Russia but also trilateral cooperation among South Korea, the North and Russia. I expect the committee to play a great role as opening an era of economic cooperation in Northeast Asia is also a move to open a shortcut to unification," the Cheong Wa Dae spokesman quoted the president as saying.

The two Koreas remain technically at war as the 1950-53 Korean War ended with an armistice, not a peace treaty. (Yonhap)