North Korea has also conducted what it called simulations with its "first tactical nuclear attack submarine"

North Korean media reported early Monday that the leader Kim Jong Un oversaw the cruise missile launches from the submarine above the East Sea Sunday with "great satisfaction", amid heightened regional tensions.

According to the Korean Central News Agency, the two missiles — Pulhwasal-3-31 — hit their target island.

They "had no impact on the security of a neighboring country and has nothing to do with the regional situation," the KCNA report noted, adding that Kim Jong-Un had "expressed great satisfaction" with the launch.

The KCNA report noted that the Pulhwasal-3-31 missiles were in the air for 7,421 seconds and 7,445 seconds, without specifying their range.

The cruise missile is a newly developed strategic weapon that Pyongyang tested for the first time Wednesday, firing multiple missiles toward the Yellow Sea.

North Korea's exact sea-based launch capabilities remain unknown.

Previous tests were carried out from older vessels, including from a submerged platform, rather than an actual submarine.

In March last year, North Korea launched two cruise missiles that flew 1,500 kilometres (930 miles), according to Pyongyang, putting all of South Korea and much of Japan within range.

North Korea also has a submarine-launched ballistic missile (SLBM) called the Pukguksong-3, with an estimated range of 1,900 kilometres. It announced a successful test of a new version of that missile in October 2021.

SLBMs can be launched from under the ocean, making them extremely mobile and hard to detect.

Proven SLBM capability would take North Korea´s arsenal to a new level, allowing deployment far beyond the Korean peninsula and a second-strike capability in the event of an attack.

North Korea has also conducted what it called simulations with its "first tactical nuclear attack submarine".

Pyongyang has accelerated weapons testing in the new year, including tests of what it called an "underwater nuclear weapon system" and a solid-fuelled hypersonic ballistic missile.

Unlike their ballistic counterparts, the testing of cruise missiles is not banned under current UN sanctions against Pyongyang.

Cruise missiles tend to be jet-propelled and fly at a lower altitude than more sophisticated ballistic missiles, making them harder to detect and intercept.

Recent months have seen a sharp deterioration in ties between the two Koreas, with both sides jettisoning key tension-reducing agreements, ramping up frontier security, and conducting live-fire drills along the border.