North Korea threatened on Friday an “unprecedentedly persistent, strong” response as South Korea and the United States gear up for annual military exercises as part of efforts to fend off the North’s growing nuclear and missile threats.

The North’s foreign ministry accused the United States of stoking tension and of using the UN Security Council (UNSC) as “a tool for illegal hostile policy” to pressure Pyongyang.

North Korea had “refrained from any special military action” this year except for regular activities, but the allies’ scheduled drills would create a “grave vortex of escalating tension,” the ministry said.

“If it is the US option to show its muscle and counter everything with muscle, the same is true of the DPRK’s option,” the ministry said in a statement carried by state media KCNA.

The ministry used the acronym of the country’s official name, the Democratic People’s Republic of Korea.

“In case the US and South Korea carry into practice their already-announced plan for military drills which the DPRK... regards as preparations for an aggression war, they will face unprecedentedly persistent and strong counteractions,” the statement said.

The ministry also warned that if the UNSC continues to be “inveigled” by Washington, it would reconsider additional actions beyond normal military activities, without elaborating.

The statement came less than two hours after South Korea announced joint tabletop exercises next week aimed at improving operations of American nuclear assets, and regular springtime drills next month.

Nuclear-armed North Korea fired an unprecedented number of missiles last year, including intercontinental ballistic missiles (ICBMs) that could strike anywhere in the United States, while resuming preparations for its first nuclear test since 2017.

The nuclear drills, called the Deterrence Strategy Committee Tabletop Exercise, are scheduled for February 22 at the Pentagon and will involve senior defence policymakers from both sides, Seoul's defence ministry said.

It would be their first such exercises since both sides agreed last year to hold them annually, with Seoul seeking to bolster confidence in American extended deterrence - its military capability, especially nuclear forces, to deter attacks on its allies.

On February 23, the officials will visit the Kings Bay naval base in Georgia that houses key nuclear submarines.

“With a focus on North Korea’s nuclear threats, both sides will have in-depth discussions on various measures to strengthen US extended deterrence, including information sharing and consultation procedures,” the ministry said in a statement.

The springtime Freedom Shield field training will separately begin in mid-March in South Korea for an 11-day run.