North Korean leader Kim Jong Un inspected the demonstration of a "new-type tactical guided weapon" on Thursday as a warning to South Korean "warmongers" to stop importing weapons and conducting joint military drills, state media said on Friday.
North Korea test-fired two new short-range ballistic missiles on Thursday, South Korean officials said, its first missile test since Kim and US President Donald Trump agreed to revive denuclearisation talks last month.
"We cannot but develop nonstop super-powerful weapon systems to remove the potential and direct threats to the security of our country that exist in the south," Kim said, according to state news agency KCNA.
The US State Department urged Pyongyang to refrain from further provocations and hoped for a resumption of working-level talks on North Korea's denuclearisation.
South Korea also urged Pyongyang to stop acts unhelpful to easing tension and said the tests posed a military threat.
The KCNA report did not mention Trump or the United States, but said Kim criticised South Korean authorities for staging joint military exercises, which are usually conducted with US troops.
Kim said the test was "a solemn warning to the south Korean military warmongers" and accused South Koreans of "double dealing" for saying they support peace but simultaneously importing new weapons and conducting military drills.
South Korea's leader should stop such "suicidal acts" and "should not make a mistake of ignoring the warning," Kim said.
Kim said he was satisfied with the rapid response and low-altitude trajectory of the weapon, which he said would make it difficult to intercept.
South Korea's defence ministry said the missiles were launched from North Korea's east coast near Wonsan city travelled about 267 miles (430 km) and 428 miles (688 km) over the sea. They both reached an altitude of 30 miles (48 km).
Seoul's National Security Council said on Thursday it believed the missiles were a new type of ballistic missile, but it would make a final assessment with the United States.
Ballistic missile tests would be a violation of U.N. Security Council resolutions that ban North Korean use of such technology. North Korea rejects the restriction as an infringement of its right to self-defence.
When asked what message the Trump administration was taking from North Korea's launch of short-range missiles, US Secretary of State Mike Pompeo told Fox News that prior to US-North Korea negotiations Pyongyang had been engaged in activity "far more dangerous for America and Japan and for South Korea".
Pompeo said when Kim met Trump at the DMZ he had agreed to "avoid launching intermediate-range and long-range ballistic missiles" and "put his negotiating team back in the game". He said fresh talks were still possible.
"You know, lots of countries posture before they come to the table," Pompeo told Fox News.
While the message is very clearly directed at Seoul, it does send signals to Washington as well, said Jenny Town, managing editor at 38 North, a project that studies North Korea.
"On some level, this is like North Korea's version of maximum pressure on South Korea and the United States."