South Korea and the United States began massive joint aerial drills on 4 December amid threats of a nuclear war from North Korea.
North Korea said on Sunday that the joint military drill of the U.S. and South Korea could trigger a nuclear war.
A commentary that appeared in state-run newspaper, Rodong Sinmun, said that the five-day military drill was "all out provocation against" the country, and it may lead to nuclear war "at any moment".
The five-day Vigilant ACE (air combat exercise) is the largest-ever combined air force drill between the allies, involving more than 230 warplanes and around 12,000 personnel, which include six F-22 Raptors and six F-35As that have been deployed temporarily to Korea for the practice, Yonhap news agency reported.
Two B-1B Lancer bombers, six EA-18G Growler electronic warfare jets, and dozens of F-15C and F-16 fighter jets have also been deployed for the drill apart from South Korea's F-15K, KF-16, FA-50 and F-5 fighters.
"It's aimed at enhancing the all-weather, day and night combined air power operation capabilities of South Korea and the U.S.," Yonhap news agency quoted a South Korea's defense ministry as saying.
The ministry added that the both sides will conduct the drills under various wartime scenarios, including simulated precision strikes on mock North Korean nuclear and missile targets.
The exercise comes less than a week after Pyongyang fired off a new intercontinental ballistic missile and claimed that it can reach the whole mainland of the United States.