North Korea said on Monday that the United States and South Korea cease large-scale military drills, describing them as a provocation that might result in "more forceful follow-up actions" from Pyongyang.
"The situation in the Korean Peninsula and its surroundings has entered a serious confrontation phase of power for power again as a result of the United States and South Korea's ceaseless and reckless military actions," North Korea's foreign ministry said in a statement carried by the country's official KCNA news agency.
On Monday, the United States and South Korea kicked up one of their largest combined military air drills, with hundreds of jets from both sides executing pretend strikes 24 hours a day for the next week.
The mission, named Vigilant Storm, will go until Friday and involve approximately 240 warplanes flying 1,600 sorties, according to the US Air Force.
Washington and Seoul believe Pyongyang is about to resume nuclear bomb testing for the first time since 2017. They have adopted a strategy of "deterring" Pyongyang through big military drills, which may increase tensions.
According to the foreign ministry, North Korea is "prepared to take all necessary measures to safeguard its sovereignty, people's security and territorial integrity from outside military threats."
"If the United States continues to engage in grave military provocations, North Korea will consider more powerful follow-up actions," North Korea's official said.
"If the United States does not want any significant developments that are not in its best interests, it should immediately halt the pointless and ineffective war exercises. Otherwise, it will be entirely responsible for all of the repercussions," the official added.
South Korean military completed the 12-day Hoguk-22 field exercises on Friday, which included fake amphibious landings and river crossings and some training with US forces.
North Korea sees the joint exercises as a full dress rehearsal for an invasion and evidence of Washington and Seoul's hostile policy. In reaction to the exercises, it has launched missiles, conducted air manoeuvres and blasted artillery into the sea.
It has repeatedly disregarded US pleas to reopen discussions over its nuclear and missile programmes, instead launching an unprecedented wave of missile tests this year.
On Monday, US State Department spokesperson Ned Price reaffirmed appeals for North Korea to return to discussions while emphasising that the US policy of pursuing total denuclearisation of the Korean peninsula has not changed.