North Korea has revealed another kind of submarine-launched ballistic missile, described by state media as "the world's most powerful weapon".

A few of the missiles were shown at a parade regulated by leader Kim Jong-un, reported state media.

The weapon's genuine abilities stay unclear, as it isn't known to have been tested.

The demonstration of military strength comes days before the inauguration of Joe Biden as US president.

It also follows a rare political meeting where Mr. Kim decried the US as his country's "biggest enemy".

Pictures delivered by North Korean state media displayed something like four enormous highly black-and-white missiles being driven past flag-waving crowds.

Investigators noted it was a formerly concealed weapon. "New year, new Pukguksong," tweeted North Korea expert Ankit Panda, using the North Korean name for their submarine-launched ballistic missiles (SLBMs).

Clad in a leather coat and fur cap, Mr. Kim is imagined smiling and waving as he watched the presentation in Pyongyang's Kim Il Sung Square, which likewise included infantry troops, artillery, and tanks.

"The world's most powerful weapon, submarine-launch ballistic missile, entered the square one after another, powerfully demonstrating the might of the revolutionary armed forces," the official Korean Central News Agency said.

The event on Thursday did not showcase North Korea's largest intercontinental ballistic missile (ICBM), which was unveiled at a much larger military parade in October. That colossal weapon is believed to be able to deliver a nuclear warhead anywhere in the US, and its size surprised even seasoned analysts when it was put on show last year.

The country's latest display of its arsenal comes at the end of a five-yearly congress of the ruling Workers' Party.

In his address to members last week, Mr. Kim had pledged to expand North Korea's nuclear weapons and military potential, outlining a list of desired weapons including long-range ballistic missiles capable of being launched from land or sea and "super-large warheads".

He also said that the US was Pyongyang's "biggest obstacle for our revolution and our biggest enemy... no matter who is in power, the true nature of its policy against North Korea will never change".

Under Mr. Kim's leadership, North Korea has made rapid progress in its weapons program, which it says is necessary to defend itself against a possible US invasion.

The unveiling of the new missiles appears designed to send the incoming Biden administration a message of the North's growing military prowess, say experts.

"They'd like us to notice that they're getting more proficient with larger solid rocket boosters," Mr. Panda tweeted, noting what appeared to be new solid-fuel short-range ballistic missiles on display too. These missiles can be launched more quickly than liquid-fuelled varieties.