South Korea's military said Thursday that the North had launched two short-range projectiles from South Pyongan province. They each flew approximately 370 kilometres (230 miles).

It was the latest in a series of launches by the North but the first since October 2, when it fired a sea-launched missile.

If confirmed, a submarine-based missile capability would change the military balance on the Korean peninsula.

Thursday's test was conducted to "verify the security of launchers' continuous fire system," the state Korean Central News Agency reported from Pyongyang.

North Korean leader Kim Jong Un, who had personally supervised previous tests of the "super-large" system, "expressed satisfaction... and sent congratulations" to the team involved, KCNA said.

Nuclear talks between Pyongyang and Washington are currently at a standstill.

Pyongyang is under multiple sets of international sanctions over its nuclear weapon and ballistic missile programmes, which it says it needs to defend against a possible US invasion.

It is demanding the easing of the measures and has repeatedly urged Washington to come forward with a new offer by the end of this year.

Kim and US President Donald Trump adopted a vaguely-worded statement on the "complete denuclearisation of the Korean peninsula" at their first summit in Singapore in June last year, but little progress has since been made.

The pair met in Hanoi in February, but no deal was reached.

Trump and Kim then agreed to restart working-level talks during a brief meeting at the Demilitarised Zone dividing the peninsula in June.

The two sides met in Sweden earlier this month but Pyongyang walked away, saying it had "no desire" to negotiate unless the United States moves to end its "hostile policies."