NORTH Korea warned of "nuke for nuke, all-out confrontation" today in a chilling escalation of tensions with the West.
Kim Jong-un's regime said war games by the US and South Korea pushed it to an "extreme red line" and threatened to retaliate with "overwhelming nuclear force".
Fears are already high after North Korea test-fired dozens of missiles, including long-range rockets designed to carry nuclear warheads as far as the US mainland.
Earlier this week US defence secretary Lloyd Austin visited Seoul and promised to deploy more advanced military tech.
He said fighter jets and aircraft carriers would strengthen joint training with South Korea.
And yesterday American B-1B nuclear bombers and stealth fighters - US F-22s and Korean F-35s - staged a show of force over the Yellow Sea.
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Pyongyang's foreign ministry hit back warning the expansion of military drills threatened to turn the region into "a huge war arsenal and a more critical war zone".
It said the deployment of strategic assets was akin to planning a nuke strike on North Korea, and would "ignite an all-out showdown", the state news agency KCNA reported.
It added the North was prepared to counter any challenge with the "most overwhelming nuclear force".
The ministry statement said: "DPRK will take the toughest reaction to any military attempt of the US on the principle of nuke for nuke and an all-out confrontation for an all-out confrontation!".
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It also warned Kim could launch more provocative demonstrations of his arsenal.
Last year's record number of missile launches included what the regime said were simulated nuclear attacks on South Korea and the US.
A huge military parade and planned launch of a spy satellite could further raise tensions, warned North Korea expert Prof Yang Moo-jin.
Commercial satellite images suggest "extensive parade preparations" are under way in Pyongyang ahead of one of the biggest state holidays, according to the 38 North website.
It said the parade could be held on the "Day of the Shining Star" on February 16, the birthday of Kim's grandfather Kim Jong-il.
Pentagon boss Austin - now in the Philippines - said: "The United States is very serious about its commitment to defending South Korea and will continue to work alongside its allies and ensure that we maintain credible and ready forces."
North Korea has insisted it is an "irreversible" nuclear power after a series of successful A-bomb tests.
Reports in October suggested the regime was gearing up for new underground tests, the first for five years.
It also fired dozens of missiles in breach of international sanctions.
The US scaled down military drills to leave room for diplomacy with Kim Jong-un.
But it has ramped them up after the North said it was "not interested in any contact or dialogue".
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South Korea said the North's threats of preemptive nuclear attacks have forced it to ensure the protection of its citizens.
Defence ministry spokesperson Jeon Ha Gyu said the latest aerial drills were aimed at demonstrating the "credibility of the US extended deterrence".