North Korea's army will immediately launch a "baptism of fire" in response to any provocation, Kim Yo Jong, the powerful sister of leader Kim Jong Un, said on Sunday, in comments carried by state news agency KCNA.
The remarks come after South Korea's military said the North fired more than 60 artillery rounds on Saturday near their disputed maritime border, following a similar volley of more than 200 there the previous day.
"Let me be clear once again that our army has its trigger already unlocked," Kim Yo Jong said in a statement carried by KCNA.
"Our army will immediate launch a baptism of fire in case of even a small provocation."
Although South Korea held its own fire drills in the sea on Friday in response to the artillery shells, the Yonhap news agency said there was no plan to do so after Saturday's events.
Friday's duelling drills sparked warnings for residents of South Korean border islands to seek cover in bomb shelters, though there was no report of shells crossing the maritime border.
In the statement, Kim denied the Saturday firing and said the North detonated explosives instead as a deception.
Hamas handed over three Israeli hostages on Saturday, whose emaciated appearance shocked Israelis following their release on live TV, in the latest stage of a ceasefire deal aimed at ending the 15-month war in Gaza.
The US Coast Guard in Alaska found the wreckage of a small plane atop frozen sea ice on Friday, after the aircraft suddenly lost altitude on Thursday and the crash killed all 10 people on board, officials said.
A US judge has temporarily allowed roughly 2,700 US Agency for International Development employees put on leave by President Donald Trump's administration to go back to work, pausing aspects of a plan to dismantle the agency.
Hamas accused Israel of multiple breaches of their ceasefire agreement on Friday, a day before the scheduled exchange of three more Israeli hostages for Palestinian prisoners in the latest stage in a fragile deal aimed at ending the war in Gaza.