Kim attended the ceremony held at the Nampho port in North Korea to celebrate the deployment of the new multipurpose destroyer Choe Hyon, state media KCNA reported.
The destroyer successfully completed military operational tests over the past 14 months, KCNA added.
The country plans to deploy another 5000-tonne destroyer named Kang Kon soon along with 10,000-tonne strategic warships, Kim said, according to the report.
Kang Kon was repaired last year after partially capsizing during a launch ceremony.
The navy had been the weakest part of North Korea's military forces, Kim said, adding its capabilities would now be "something incredible beyond imagination."
"Building a modernised naval base has emerged as a desperate and essential task," Kim said.
He said officials of the ruling Workers' Party's Central Committee discussed plans to build new naval bases at a meeting on Monday.
The most important change for the navy would be a shift in its status, role and scope of operations, Kim said, without elaborating.
The navy's nuclearisation is "advancing along its own course," contributing to the country's nuclear deterrence, he said.
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