NORTH Korea has tested its nuclear underwater attack drone in a chilling warning shot to the US, Japan and South Korea carrying out war drills.
The "Haeil-5-23" system - which is reportedly capable of sparking a "radioactive tsunami" - was tested in response to three days of joint war drills by the US and its allies.
North Korea said the military exercises were "seriously threatening the security” of the country.
The regime claims it has been developing the weapons system in the East Sea, or Sea of Japan, according to .
The latest test appears to be a new model of the nuclear-capable underwater drone called "Haeil" - which translates to "tsunami" - that was tested twice last year.
During one of the drills, the drone reportedly cruised underwater for more than 59 hours and detonated in waters off the east coast.
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Designed to make sneak attacks in enemy waters, North Korea's state media claims "Haeil" can wipe out enemy vessels and ports by creating a large radioactive wave through an underwater explosion.
Tensions on the Korean Peninsula have risen to their highest point in years - with Kim Jong-un accelerating his weapons testing and threatening all-out nuclear war.
The US and its Asian allies have responded by strengthening their combined military exercises - which Kim calls rehearsals for invasion.
A North Korean defence ministry spokesman accused the US, South Korea and Japan of "getting frantic" with their latest three-day war driills - and warned of "catastrophic consequences".
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The defence ministry said: "We strongly denounce the US and its followers for their reckless acts of seriously threatening the security of the DPRK from the outset of the year and sternly warn them of the catastrophic consequences to be entailed by them."
The spokesman said its army's "various maritime and underwater responsive actions will continue to deter the hostile military manoeuvres of the navies of the US and its allies".
North Korea's alleged nuclear attack drone is among a range of weapon systems demonstrated in recent years as Kim expands his arsenal of nuclear-capable weapons.
South Korea's military has insisted the North has exaggerated the capabilities of the drone.
The drone test came days after Jong-un announced he would scrap his country's long-standing goal of a peaceful unification with South Korea.
Tensions are running high as Kim continues to step up pressure on Seoul, declaring it the "principal enemy".
He threatened to "annihilate" it if provoked and vowed to enhance his country's ability to deliver a nuclear strike on the US and America's allies in the Pacific.
Earlier in January, Kim's sister - Kim Yo-Jong - pledged to unleash an "immediate military strike" on South Korea over the "slightest provocation".
The close ally of the dictator said North Korea wouldn't hesitate to attack its "enemy" as tensions explode on the border.
Experts say that Kim is trying to stoke up anger by conducting more missile tests and possibly launching small-scale physical attacks on its neighbour to meddle with South Korea' s elections in April.
Last week, North Korea fired a new intermediate-range, solid-fuel hypersonic missile - which Washington, Seoul and Tokyo condemned as a serious violation of UN Security Council resolutions.
Pyongyang's isolated government is also forging closer ties with Moscow and it attempts to solidify its position in the growing anti-Western axis of evil.
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On December 29 and January 2, Russia used North Korean missiles to blitz Ukraine for the first time, leaving at least 50 people dead.
UK Defence Secretary Grant Shapps said: “The world turned its back on Russia, forcing Vladimir Putin into the humiliation of going to North Korea to keep his illegal invasion going.”