North Korea has reportedly deployed its first nuclear attack submarine as part of a fleet that patrols the Sea of Japan, between the Korean peninsula and Japan, state media reported.

Reuters reported that news agency KCNA said Kim Jong Un attended the submarine’s launch ceremony Wednesday.

The North Korean leader said arming the country’s navy with nuclear weapons was a very high priority, promising to send more vessels armed with nuclear weapons to the military branch.

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"The submarine-launching ceremony heralded the beginning of a new chapter for bolstering up the naval force of the DPRK," KCNA said, using the initials of the North's official name, the Democratic People's Republic of Korea.

The submarine has been named after one of the country’s historical figures, Hero Kim Kun OK, and Kim said it will perform as "one of core underwater offensive means of the naval force."

Analysts saw signs in 2016 that at least one new submarine was being built, then in 2019, state media showed Kim inspecting a submarine reportedly built under his "special attention" for operations off the country’s east coast.

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Photos taken of a North Korean shipyard in August 2019 suggested the country could be building a submarine that could potentially be capable of launching a nuclear missile.

The images showed vessels and cranes that could be used to haul a missile out to sea for launch. The satellite photos also confirmed, at the time, state media reports about a newly built submarine.

In March, North Korea test fired two "strategic cruise missile" from a submarine near Kyongpho Bay off the country’s east coast, and according to the state-run Korean Central News Agency (KCNA), the drill confirmed the reliability of the weapon system and examined the underwater-to-surface offensive operations of submarine units.

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It is not clear whether North Korea has fully developed nuclear warheads small enough to fit on submarine launched ballistic missiles (SLBMs) or short-range SLBMs and cruise missiles.

Analysts suggest nailing down the miniaturized nuclear warheads will likely be a goal if North Korea intends to resume nuclear testing.

While the country has a large submarine fleet, Submarine No. 841 is the first tactical nuclear attack submarine.

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There has also only been one sub, the experimental ballistic missile submarine 8.24 Yongung, that is known to have launched a missile.

Missile Defense Advocacy Alliance senior research fellow Tal Inbar posted images of the new submarine making its way into the water.

In the post, Inbar said there was a huge sail with room for several ballistic and cruise missiles.

"It won’t be long before we will see it launch missiles," he added.

Reuters contributed to this report.