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North Korea is not frightened by U.S. warnings that pre-emptive military action is on the table, its foreign ministry said Tuesday, describing its expanding nuclear program as a “treasured sword of justice.”

A spokesman for the rogue regime dismissed Secretary of State Rex Tillerson’s comment Friday that an elevated weapons threat “would be met with an appropriate response."

“If the businessmen-turned-U.S. authorities thought that they would frighten [North Korea], they would soon know that their method would not work,” the foreign ministry said according to state news agency KCNA.

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The regime “has the will and capability to fully respond to any war the U.S. would like to ignite,” it added. “The U.S. should face up to the situation … with its eyes wide open.”

It comes after leader Kim Jong Un announced the ground test of a "high-thrust" rocket engine on Saturday.

Kim Jong Un looks at a rocket warhead tip. KCNA / Reuters, file

“The world will soon witness what eventful significance the … recent ground jet test of Korean-style high-thrust engine will carry,” KCNA said Tuesday. “The nuclear force of [North Korea] is the treasured sword of justice and the most reliable war deterrence.”

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U.S. Ambassador to the U.N. Nikki Haley said North Korea was the “number one threat” to the U.S. and that military action was an option if there was no co-operation.

Her comments were echoed by former defense secretary William Cohen, who told CNBC that North Korea’s military escalation was “the most dangerous issue we have facing us today.”

North Korea conducted two nuclear test explosions and 24 ballistic missile tests during 2016, and experts say it could have a nuclear-tipped missile capable of reaching the U.S. mainland within a few years.

In a separate statement Tuesday, KCNA accused the CIA of cyber-warfare.

“The U.S. is a hacking empire and the worst rogue state which stoops to any [level] to realize its ambition for world domination,” it said in an editorial comment.