North Korean leader Kim Jong Un has warned his country will end its suspension of nuclear and long-range missile tests.
Amid stalled nuclear talks with the United States, Mr Kim left the door open for future negotiations but also threatened there would be "shocking" action.
Mr Kim gave no clear indication of when such tests could resume but said North Korea would soon reveal a new "strategic weapon" in response to "gangster-like" US pressure.
His comments, reported in state media on Wednesday, were made during a four-day top party meeting in Pyongyang.
It followed the North's end-of-year deadline for denuclearisation talks with the US.
Lee Sang-Min, spokesman for South Korea's Unification Ministry, warned North Korea that showcasing its new weapon would be bad news for diplomacy.
Mr Kim did not specify what the new weapon was but it is believed that the country has been increasing its short-range weapon capability in recent months.
North Korea is estimated to have 40-50 nuclear bombs in its arsenal, as well as developing Intercontinental ballistic missiles, capable of reaching US mainland.
A UN spokesman said Secretary General Antonio Guterres "very much hopes that the [nuclear] tests will not resume".
Earlier this week, Mr Kim called on North Korea to install "offensive measures" to protect the country.
It followed the announcement in December that North Korea had carried out two "crucial tests" at its long-range rocket launch site, which Pyongyang said would strengthen its nuclear deterrent.
On Tuesday, US President Donald Trump urged Mr Kim to stick to his alleged agreement, made in June 2018, to denuclearise.
Mr Kim warned the US that if it persists with its "hostile policy", then there will "never be denuclearisation on the Korean peninsula", according to the state-run, Korean Central News Agency.
He added North Korea will "steadily develop necessary and prerequisite strategic weapons for the security of the state until the US rolls back its hostile policy".
The US has refused to remove any sanctions on North Korea over its continued nuclear policy.
Cover Image: Library image of Kim Jong-un (Picture: PA).