North Korea has fired a submarine-launched ballistic missile into waters off the coast of Japan, South Korea’s military has said.

The launch comes weeks after South Korea unveiled its own such weapon.

Pyongyang unveiled a “new” type of submarine-launched missile in January, describing it as “the world’s most powerful weapon”.

It comes as South Korea, Japan and US intelligence chiefs reportedly meet in Seoul to discuss North Korea.

In recent weeks, Pyongyang has embarked on a flurry of tests of what it claims to be hypersonic and long-range cruise missiles, and anti-aircraft weapons.

Some of these tests violate strict international sanctions.

North Korea is specifically prohibited by the United Nations from testing ballistic missiles as well as nuclear weapons.

On Tuesday South Korea’s Joint Chiefs of Staff said one missile was launched from the port of Sinpo, in the east of North Korea where Pyongyang usually bases its submarines. It landed in the East Sea, also known as the Sea of Japan.

South Korean media reported that this particular missile is believed to have travelled between 430 and 450km at an apogee – or maximum height – of 60km.

It is unclear if the missile was launched from a submarine or from an underwater platform.

Japan’s Prime Minister Fumio Kishida said there were two ballistic missiles fired, calling the launches “very regrettable”.

Why is ‘submarine-capable’ significant?

In October 2019 North Korea tested a submarine-launched ballistic missile, firing a Pukguksong-3 from an underwater platform.

At the time, state news agency KCNA said it was fired at a high angle to “contain external threat”.

If the missile had been launched on a standard trajectory, instead of a vertical one, it could have travelled around 1,900 km (1,200 miles). That would have put all of South Korea and Japan within range.

Being launched from a submarine can also make missiles harder to detect, and allows them to get closer to other targets.

How has South Korea reacted to the frequent launches?

The launch comes as South Korea develops its own weapons, in what observers say has turned into an arms race on the Korean peninsula.

Seoul is holding what is said to be South Korea’s largest defence exhibition ever this week. It will reportedly unveil a new fighter jet as well as guided weapons like missiles. It is also due to launch its own space rocket soon.

North and South Korea technically remain at war as the Korean War, which split the peninsula into two countries and which saw the US backing the South, ended in 1953 with an armistice.

North Korean leader Kim Jong-un said last week that he did not wish for war to break out on the Korean peninsula again, but said his country needed to continue developing weapons for self-defence against enemies, namely the US which he accused of hostility.

The US envoy to North Korea, Sung Kim, is currently on his way to South Korea to discuss how to restart dialogue with Pyongyang, including on whether there should be a formal declaration of the end of the Korean War.

In the last 24 hours, he has reiterated the stance of the Biden administration that it is open to meeting with North Korea without pre-conditions.

Previous talks between the US and North Korea broke down due to fundamental disagreements on denuclearisation.

The US wants North Korea to give up its nuclear