North Korea has launched its first "tactical nuclear attack submarine" as part of its effort to strengthen its naval force, the state news agency KCNA announced on Friday.

North Korean leader Kim Jong Un attended the submarine-launching ceremony on Wednesday, according to KCNA.

During the festive ceremony that involved confetti and balloons, he stressed "the strategic and tactical plan to continuously enhance the modernity of underwater and surface forces and push forward with the nuclear weaponization of the Navy in the future."

On Thursday, Kim inspected the submarine as it was preparing for a test cruise.

Submarine No. 841 is named Hero Kim Kun Ok after a North Korean historical figure. According to Kim, it will carry out its combat mission as "one of core underwater offensive means of the naval force" of North Korea.

The submarine was assigned to the fleet patrolling the waters between the Korean peninsula and Japan, state media said.

It was not immediately clear what missiles the new submarine would be armed with. North Korea has test-fired several long-range submarine-launched ballistic missiles (SLBMs), as well as short-range SLBMs and cruise missiles that can be fired from submarines.

North Korea has a large submarine fleet but only the experimental ballistic missile submarine 8.24 Yongung (August 24th Hero) is known to have launched a missile.

The South Korean military said that they believe that Wednesday's submarine was launched from within the Sinpo shipyard in southern North Korea.

Kim Inae, a spokesperson at Soeul's Unification Ministry, which handles inter-Korean affairs, said that North Korea's move was "deplorable."

She expressed her dismay at Kim Jong Un channeling his limited resources into developing weapons while ignoring the state of his impoverished people.

When asked if Russia may have assisted North Korea on its new submarine, the spokesperson did not provide a specific answer.