North Korea has conducted a "strike drill" for multiple launchers and tactical guided weapons into the East Sea in a military drill supervised by leader Kim Jong-un on Saturday, the North's state media reported on Sunday.
The purpose of the drill was to test performance of "large-calibre long-range multiple rocket launchers and tactical guided weapons by defence units," the Korean Central News Agency said, implying that the latest firing was not the long-range ballistic missiles that have been seen as a threat to the United States.
Kim gave an order of firing and stressed the need to "increase the combat ability so as to defend the political sovereignty and economic self-sustenance" of North Korea in the face of threats and invasions, the report said.
The statement came a day after the latest firing, which analysts interpreted as an attempt to exert pressure on Washington to give ground in negotiations to end the North's nuclear programme after a summit in February ended in failure.
"Yes, the tests were the most serious since the end of 2017, but this is largely a warning to Trump that he could lose the talks unless Washington takes partial denuclearisation steps offered by Kim," said Shin Beom-chul, a senior fellow at the Asan Institute for Policy Studies.
"A resumption of long-range test could be next unless Kim gets what he wants soon."
North Korea had maintained a freeze in nuclear and ballistic missiles testing in place since 2017, which US President Donald Trump has repeatedly pointed out as an important achievement from his engagement with Pyongyang.
The latest firing prompted Seoul to call on its communist neighbour to "stop acts that escalate military tension on the Korean Peninsula" on Saturday, while Trump said in a Twitter post that he was still confident he could have a deal with Kim.
"I believe Kim realises the great economic potential of North Korea, & will do nothing to interfere or end it," Trump wrote. "He also knows that I am with him and does not want to break his promise to me. Deal will happen!"
The projectiles, fired from the east coast city of Wonsan, flew about 70km to 200km in a north-easterly direction, South Korea's Office of the Joint Chiefs of Staff said in a statement on Saturday.
The South Korean military initially described it as a missile launch, but subsequently gave a vaguer description and said it was conducting joint analysis with the United States of the latest launches.
Experts say the projectiles appeared to come from multiple rocket launchers, and were not ballistic missiles.
Talks stalled after a second summit between Kim and Trump in Hanoi in February failed to produce a deal to end Pyongyang’s nuclear programme in return for sanctions relief.
North Korea demanded Washington lift the US-led sanctions in return for a partial dismantling of its nuclear weapons programme, while the United States wanted a quick rollback of the North’s entire nuclear weapons programme.
The North's last missile launch was in November 2017, when it tested an intercontinental ballistic missile. Soon after that missile test, the North declared that its nuclear force was complete, after which Pyongyang extended an olive branch to the South and the United States.