At a key party congress in January 2021, Kim outlined a five-year defence development plan, calling for the development of smaller and lighter nuclear weapons for "more tactical uses."

Seoul, Tokyo and Washington have ramped up combined naval exercises in recent weeks, infuriating Pyongyang which sees them as rehearsals for invasion and justifies its blitz of missile launches as necessary "countermeasures".

KCNA said the blitz of recent tests were a response to those countries' joint drills, adding the exercises were "under the simulation of an actual war".

North Korean army units involved in "the operation of tactical nukes staged military drills from September 25 to October 9 in order to check and assess the war deterrent and nuclear counterattack capability of the country, which comes to be a severe warning to the enemies," a report in the official KCNA said.

"Kim Jong Un, general secretary of the Workers' Party of Korea and chairman of its Central Military Commission, guided the military drills on the spot," it added.

With talks long stalled, Pyongyang has doubled down on its banned weapons programmes, firing an intermediate-range ballistic missile over Japan last week, with officials and analysts warning it has completed preparations for another nuclear test.

The seven recent tests -- which KCNA said were "launching drills of the tactical nuclear operation units" -- allowed North Korea's nuclear forces to display their "militant effectiveness and actual war capabilities," KCNA added.