The threat was in response to comments from CIA Director Mike Pompeo, who said last week that the Trump administration needed to find a way to separate Kim from his growing nuclear stockpile.
"As for the regime, I am hopeful we will find a way to separate that regime from this system," Pompeo said. "The North Korean people I'm sure are lovely people and would love to see him go."
KCNA reported that a spokesman from the North Korean Foreign Ministry said, "The DPRK legally stipulates that if the supreme dignity of the DPRK is threatened, it must preemptively annihilate those countries and entities that are directly or indirectly involved in it, by mobilizing all kinds of strike means including the nuclear ones."
"Should the US dare to show even the slightest sign of attempt to remove our supreme leadership, we will strike a merciless blow at the heart of the US with our powerful nuclear hammer, honed and hardened over time," the foreign ministry spokesman added.
North Korea's threat comes amid an ongoing assessment from the US intelligence community that North Korea has accelerated its intercontinental range ballistic missile program
A spokesperson for Defense Intelligence Agency declined to comment directly on a report from The Washington Post
that the agency's latest assessment concludes Pyongyang will have a nuclear-capable intercontinental ballistic missile as early as next year but admitted that Pyongyang's missile capabilities are progressing.
"North Korea's recent test of an intercontinental range ballistic missile -- which was not a surprise to the intelligence community -- is one of the milestones that we have expected would help refine our timeline and judgments on the threats that Kim Jong Un poses to the continental United States," Scott Bray, National Intelligence Manager for East Asia, ODNI, told CNN.
"This test, and its impact on our assessments, highlight the threat that North Korea's nuclear and ballistic missile programs pose to the United States, to our allies in the region, and to the whole world. The intelligence community is closely monitoring the expanding threat from North Korea," Bray added.
US Ambassador to the United Nations Nikki Haley warned lawmakers last month that the North Korea's missile program may be advancing ahead of previous estimates that put Kim's unpredictable regime three to five years away from achieving its ambition of being able to deliver a nuclear weapon to the US.
"You are more optimistic saying it is multiple years before an ICBM (intercontinental ballistic missile) comes forward," she said while testifying before the House Foreign Affairs Committee. "I think it's going to happen sooner, because they are on target to do that."
Missile test coming?
North Korea also appears to be preparing for another missile test
, according to a US Defense official who said that transporter vehicles carrying ballistic missile launching equipment were seen arriving in Kusong, North Korea last week.
The official said that when such equipment is seen, a launch could occur within six days, which would coincide with the upcoming July 27 North Korean Holiday celebrating the armistice which ended the Korean War.
CNN reported earlier this month
that US intelligence indicated that North Korea is making preparations for another intercontinental ballistic missile (ICBM) or intermediate range missile test.
Two administration officials familiar with the latest intelligence confirmed they'd seen indicators of test preparations.
US satellites have detected new imagery and satellite-based radar emissions indicating that North Korea may be testing components and missile control facilities for another ICBM or intermediate launch, officials said.
Updated military options for Trump
Last month, CNN reported that US military updated its options for North Korea with the goal of giving President Donald Trump options for a rapid response, according to two US military officials at the time.
The options, which include a military response, will be presented to the president if Pyongyang conducts an underground nuclear or ballistic missile test that indicates the regime has made significant progress toward developing a weapon that could attack the US, they said.
On Saturday at the Aspen Security Forum, Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford said at some point military plans would be presented to Trump on how to deal with North Korea: "We'll go to him at some point with a range of military options and at the same time I'd expect Secretary Tillerson would talk about other diplomatic options available should the path we're on not succeed."
But a US preemptive attack continues to be highly problematic option because the Pentagon has long believed North Korea would in turn attack South Korea.
Diplomatic efforts stop North Korea's march toward a long-range nuclear missile have also proven unsuccessful to date -- particularly when it comes to US reliance on China to pressure Pyongyang.
Recent US intelligence assessments indicate that North Korea would not be able to follow through with its most recent threat to hit the US with a nuclear weapon -- but the window to prevent Kim from realizing his nuclear ambitions is rapidly closing.