North Korean leader Kim Jong Un has inspected a shipyard and stressed the importance of strengthening the country's naval force, saying it is "the most important issue" in stepping up "war preparations," state-run media said Friday.

His call for modernizing the country's shipbuilding industry during a visit to the dockyard in the western city of Nampo was made as Pyongyang repeatedly denounced the recent dispatch of a U.S. nuclear-powered submarine to South Korea.

Undated photo shows North Korean leader Kim Jong Un (L, front) inspecting a shipbuilding yard in Nampo, North Korea. (KCNA/Kyodo)

The official Korean Central News Agency did not reveal when Kim inspected the shipyard. The leader received detailed reports on the building of various warships and called for completing a five-year national defense plan from 2021 that includes the development of nuclear submarines.

Kim stressed that strengthening the country's shipbuilding industry is "an important guarantee and precondition" for implementing the policy of the ruling Workers' Party of Korea on building national defense and the economy, KCNA said.

Last Sunday, the leader observed the test firing of submarine-launched strategic cruise missiles with senior navy and ruling party officials and directed tasks to be completed regarding the building of a nuclear-powered submarine and other new-type warships, according to the news agency.

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