His comments follow a four-day meeting of party officials in Pyongyang, during which Kim Jong-un suggested that North Korea would lift its moratoriums on nuclear and intercontinental ballistic missile tests, contrary to what was agreed with Donald Trump. He also said it is "foolish to barter away national security in exchange for food and money".
"This was Kim clearly rejecting the Trump administration's proposal offering North Korea a bright future for its economy", said Shin Bum-chul, who studies inter-Korean relations at the Asan Institute for Policy studies and is a former researcher in South Korea's defence ministry.
Now, pressure is mounting on Trump to acknowledge that his strategy has failed and to change course, amid renewed warnings from Kim this week that the North would soon unveil a "new strategic weapon," which analysts said could mean a long-range ballistic missile test.
A USA official, speaking on condition of anonymity, said there were no indications that North Korea was preparing for an imminent long-range missile test.
Donald Trump and Kim Jong-un talk before a meeting in the Demilitarized Zone (DMZ) on June 30, 2019.
Kim past year had said the North would pursue a "new way" if the Trump administration doesn't make concessions to salvage the negotiations by the end of December.
United Nations spokesman Stephane Dujarric said the signals from North Korea had left Secretary-General Antonio Guterres "deeply concerned".
"We will reliably put on constant alert the powerful nuclear deterrent capable of containing the nuclear threats from the USA and guaranteeing our long-term security, noting that the scope and depth of bolstering our deterrent will be properly coordinated depending on the USA future attitude to the DPRK", Kim was quoted as saying.
Alongside the North Korean leader's latest sabre-rattling this week was a stunning admission: Efforts to engage the United States had failed. Some said that the North appeared to be threatening to cross a "red line" that Washington has apparently drawn in denuclearization talks but leaving room for the two sides to find diplomatic solution to the current standoff.
He often highlight's the weapons testing moratorium as a sign his policy of engagement with North Korea was working.
The "5th Plenary Meeting of the 7th Central Committee of the Workers' Party of Korea" was held in the capital city of Pyongyang where Kim expressed his impatience with the slow pace of nuclear-disarmament negotiations with the U.S. Kim told the ruling party officials that their country would never give up its security for economic benefits.
"But once you reached a strategic (nuclear) status and need to consolidate it, you do it quietly while holding back provocative tests, like the way India and Pakistan did it", Koh said.
The allies have scaled down their major military exercises since 2018 to create space for diplomacy, but North Korea considers such drills to be rehearsals for an invasion and insists even the smaller drills violate agreements between the leaders. "The U.S. and North Korea are fundamentally at odds in their strategic objectives". No speech was broadcast as of Wednesday afternoon, though Koh said a broadcast or statement could come later.