This grand display of the regime's military might came on the heels of its most important political event, the party congress, which officially closed on Tuesday with Kim proclaiming a redoubling of work on the country's nuclear and conventional weapons programs.

North Korea's state media reported on January 15 that the country's military parade was held at Kim Il Sung Square in the capital Pyongyang the previous day.

Earlier, a South Korean government source said the North appeared to have staged a military parade on Thursday at around 6 p.m.

North Korea has not fired off a long-range weapon since November 2017, when it tested a missile analysts say is capable of striking much, if not all, of the continental United States. North Korean state TV hasn't released footage of the event, and the South Korean and USA militaries haven't yet provided assessments of the weapons displayed by the North.

Wearing a shiny black leather jacket and fur hat, North Korean leader Kim Jong Un attended the Thursday event, which marked the end of a major multiday meeting of the ruling Workers' Party.

But the North has been developing submarine-launched ballistic missile systems for years.

At the parade, thousands of marching troops were confirmed not to have worn protective face masks, as North Korea claims the novel coronavirus that causes the COVID-19 disease has not made inroads into the nation.

It was the first time a military parade occurred in conjunction with a Party Congress.

One of the reasons for this stalemate has been the lack of consensus on the concessions North Korea should make in exchange for lifting worldwide sanctions against it.

Should Biden choose to open talks with North Korea, some analysts remain skeptical of the true potential to deliver long-term results.

The agency also said the parade featured other missiles capable of "thoroughly annihilating enemies in a pre-emptive way outside (our) territory".

Soldiers march during a military parade in Pyongyang on Jan 14 2021

The newly unveiled SLBM was nearly the same body length as the Pukkuksong-4, but the warhead is believed to be longer, raising the possibility that the missile can carry multiple warheads or has an extended range.

In addition to the usual phalanxes of troops, rows of tanks, armored vehicles and rockets, there were several new weapons introduced to the public at the parade. The KN-23, with a range of around 400 to 600 kilometers, is considered a tactical missile aimed at South Korea.

Asked about the new SLBM, Japan's top government spokesman, Chief Cabinet Secretary Katsunobu Kato, said Tokyo was aware of the display and added that it was working with the USA and others to analyze the development.

However, KCNA's description does not mention any intercontinental ballistic missile (ICBM), suggesting that the parade was on a smaller scale than that of last October.

Noh Kyu-duk, South Korea's chief nuclear negotiator, spoke by phone with US Deputy Secretary of State Stephen Biegun on Friday and discussed North Korea issues following a key party congress in the communist state, the foreign ministry said.

A working SLBM on a nuclear-powered submarine would be a strategic game-changer, enabling Pyongyang to launch a surprise attack from close to the United States or carry out a strike even if its land-based forces had been destroyed.

Kim's comments are likely meant to pressure the incoming U.S. government of Joe Biden, who has previously called the North Korean leader a "thug" and accused Trump of chasing spectacle rather than meaningful curbs on the North's nuclear capabilities.

Kim Jong Un has rolled out a lot of new missiles in recent months, including at least one more this week.

For the incoming Biden administration in the United States, denuclearization negotiations with North Korea will be immensely hard.

The North also displayed a variety of solid-fuel weapons created to be fired from mobile land launchers, which potentially expands the North's capabilities to strike targets in South Korea and Japan, including US military bases there. "With its growing military capabilities, Pyongyang will be more hard to deter and negotiate with in the New Year", Leif-Eric Easley, a professor at Ewha University in Seoul, told The Diplomat.

During the party congress, Kim unveiled plans to pursue more sophisticated military assets.