The comments came just a week after Kim warned Pyongyang would not hesitate to launch a nuclear attack if "provoked" with nukes.

Kim made the comments at the North's ongoing year-end party meeting, where he is expected to unveil key policy decisions for 2024.

Kim asked the party to "further accelerate the war preparations" across sectors, including nuclear weapons and civil defense, Pyongyang's official Korean Central News Agency reported.

He also stressed that the "military situation" on the Korean peninsula had become "extreme" due to "unprecedented" anti-North confrontations with Washington.

Seoul, Tokyo and Washington have ramped up defence cooperation in the face of a record-breaking series of weapons tests by Pyongyang this year and recently activated a system to share real-time data on North Korean missile launches.

Earlier this month, a US nuclear-powered submarine arrived in the South Korean port city of Busan, and Washington flew its long-range bombers in drills with Seoul and Tokyo.

The North has previously described the participation of US strategic assets -- such as B-52 bombers -- in joint drills on the Korean peninsula as the "intentional nuclear war provocative moves of the US".

Pyongyang this year successfully launched a reconnaissance satellite, enshrined its status as a nuclear power in its constitution, and test-fired the most advanced intercontinental ballistic missile (ICBM) in its arsenal.

Kim earlier this week defined 2023 as a "year of great turn and great change" in which Pyongyang saw "eye-opening victories".

Last week, the United Nations atomic agency said a second reactor at North Korea's Yongbyon nuclear facility appeared to be operational, calling it "deeply regrettable."

- 'Nuclear confrontation' -

At last year's year-end party meeting, Kim had called "for an exponential increase of the country's nuclear arsenal".

The United States and South Korea earlier this month held the second meeting of their Nuclear Consultative Group in Washington, where they discussed nuclear deterrence options in the event of conflict with the North.

They warned that any nuclear attack from Pyongyang on the United States or South Korea would result in the end of the Kim regime.

A spokesperson for North Korea's defence ministry then slammed the allies' plans to expand annual joint military exercises next year to include a nuclear operation drill, calling it "an open declaration on nuclear confrontation".

Pyongyang declared itself an "irreversible" nuclear power last year and has repeatedly said it will never give up its nukes programme, which the regime views as essential for its survival.

The United Nations Security Council has adopted many resolutions calling on North Korea to halt its nuclear and ballistic missile programmes since it first conducted a nuclear test in 2006