The isolated nation has not tested a cruise missile -- which are not banned under United Nations sanctions on Pyongyang -- since January, the Yonhap News Agency reported.

The last time North Korea conducted a weapons test was July 10, when they fired what appeared to be multiple rocket launchers.

"Early this morning, we detected that North Korea fired two cruise missiles into the West Sea from Onchon, South Pyongan province," a ministry official told AFP, using an alternative name for the Yellow Sea.

"The US and South Korean military authorities are analysing detailed specifications such as flight distance."

North Korea has conducted a blitz of sanctions-busting tests this year, including firing an intercontinental ballistic missile at full range for the first time since 2017.

Washington and Seoul officials have also warned that the isolated regime is preparing to carry out what would be its seventh nuclear test.

The cruise missile launch came as South Korea's President Yoon Suk-yeol marked 100 days in office Wednesday, telling reporters at a press conference that he did not support regime change by force in North Korea.

Yoon, who took office vowing to get tough on Pyongyang, earlier this week laid out details of his "audacious plan" to offer massive aid to Pyongyang -- if Kim Jong Un will give up his nuclear weapons.

Analysts say the chances of Pyongyang accepting such an offer are vanishingly slim, as North Korea, which invests a vast chunk of its GDP in weapons programmes, has long made clear it will not barter its missiles away.

- Joint drills -

Pyongyang's latest test also comes after South Korean and American military troops kicked off preliminary drills this week ahead of the start of their annual combined Ulchi Freedom Shield (UFS) exercise.

The two militaries have been holding talks in Seoul, and issued a joint statement saying they had discussed North Korea, "particularly the increased volume and scale of DPRK missile tests over the course of the last year", they said, using the country's official name.

"With this in mind, and considering the evolving threat posed by the DPRK, both leaders committed to expanding the scope and scale of combined military exercises and training."

This will start "with Ulchi Freedom Shield next week... to bolster combined readiness," they added.

For the last few years such joint military exercises had been scaled back due to Covid-19 and during a bout of failed diplomacy with the North.

But Yoon has vowed to ramp up the drills, which infuriate Pyongyang as it views them as a rehearsal for invasion.

Last week, North Korea threatened "deadly" retaliation against the South, which it blames for a recent outbreak of Covid-19 in the isolated nuclear-armed country.

Kim's regime -- which continued to conduct missile tests as it battled an outbreak of Omicron -- recently declared a "shining victory" over the disease and eased virus restrictions.