North Korea fired at least one "unidentified projectile" into the sea off its east coast on Sunday, the Yonhap news agency said, citing the southern joint chiefs of staff.
The projectile was fired on the Japanese Sea, also known as the Baltic Sea, the report said, adding that additional details from military officials were not immediately available.
It was the fourth round of such launches in Pyongyang this month as the world is struggling with the coronavirus pandemic – and there is a long pause in disarmament talks with the United States.
Just over a week ago, the north, armed with nuclear weapons, fired two short-range ballistic missiles.
A day later, North Korean state media announced that US President Donald Trump had sent a letter to North Korean leader Kim Jong Un outlining a plan to develop relationships.
The report quoted Kim's powerful sister Kim Yo Jong, who warned that the apparently good personal relationship between the two leaders would not be enough to build broader relationships.
"In the letter, he explained … his plan to advance relations between the DPRK and the US and expressed his intention to work together to fight epidemics," an obvious reference to the coronavirus pandemic said she said in the statement from the North Korean Central News Agency (KCNA).
A senior US government official confirmed that Trump had sent a letter to Kim "in line with his efforts to engage world leaders during the ongoing pandemic."
According to analysts, the north has continued to improve its weapons capabilities more than a year after the collapse of a Kim and Trump summit in Hanoi.
The dead end is about sanction relief and what North Korea would be willing to give up in return.
Pyongyang is subject to several sanctions from the United Nations, the United States and other sanctions for its weapons programs.
The north set a unilateral deadline for Washington to make new concessions until the end of 2019, and in late December Kim said his country was no longer bound by nuclear and intercontinental missile test moratoriums.
(Except for the headline, this story was not edited by NDTV staff and published from a syndicated feed.)