South Korea's military said that North Korea fired a projectile into its eastern sea, a likely effort to advance its weapons programme while also challenging the young Donald Trump administration in Washington.
The South's Joint Chiefs of Staff said in a statement that the projectile was fired from an area in the country's western region around Banghyon, North Pyongan Province, which is where South Korean officials have said the country test launched its powerful midrange missile Musudan on October 15 and 20.
An official from Seoul's Defense Ministry says it isn't clear whether the projectile was a ballistic missile, though the US military confirmed they had detected a missile test by North Korea.
A US defence official said they are assessing the launch.
Japan's Chief Cabinet Secretary Yoshihide Suga has told reporters the missile test-fired by North Korea did not hit Japanese territorial seas."We can confirm that we did detect a missile launch from North Korea," the official said, speaking on condition of anonymity. "We are assessing and will have more information soon."
South Korea's Yonhap news agency says that the Japanese government confirmed that the missile fell in seas between the Korean Peninsula and Japan.
South Korea's Joint Chiefs of Staff says South Korean and US military officials are analysing further details from the launch.
In response to the launch, South Korea held a National Security Council meeting at the presidential Blue House, which was chaired by Kim Kwan Jin, the presidential national security director.
The North conducted two nuclear tests and a slew of rocket launches last year in continued efforts to expand its nuclear weapons and missile programmes.
Kim Dong-yeop, an analyst at the Institute for Far Eastern Studies in Seoul, said that the projectile could be a Musudan or a similar rocket designed to test engines for an intercontinental ballistic missile that could hit the US mainland.
North Korean leader Kim Jong Un said in his annual New Year's address that the North's preparations for launching an intercontinental ballistic missile have "reached the final stage."