SEOUL, Sept. 13 (UPI) — North Korea issued a warning after the United States flew two B-1 bombers over South Korea on Tuesday.

The B-1B Lancers, part of a U.S. plan of “extended deterrence” against North Korea provocations, flew with U.S. F-16 and South Korean F-15 fighters over Osan Air Base, CNN reported.

But the supersonic bombers may be rattling the North Korean leadership.

Early Wednesday, local time, Pyongyang’s state-controlled news agency KCNA condemned the exercise and warned the United States and South Korea to “not act rashly,” according to Yonhap news agency.

“The U.S. imperialists are attempting to rationalize their invasion ambition, and as a pretext and in an act that shows their true intentions, they are pushing strategic bombers into South Korean airspace and, in the process, trying to find an opportunity for a preemptive strike,” the North Korean statement read.

North Korea stated the U.S. intention to attack is the reason “nuclear aircraft carriers” are being deployed “one after another.”

Pyongyang also said the “U.S. imperialist lunatics who are jumping around and losing all sight of distinctions, are acting blindly and engaging in extremely provocative acts that have placed the Korean peninsula in a situation that at every moment is drawing closer to an explosive phase.”

North Korea added its troops have a “perfect means of military response” and that they are “keenly watching” the “reckless maneuvers.”

The Air Force has previously deployed strategic bombers to South Korea in response to North Korea provocations, and the deployment is taking place after North Korea conducted its fifth nuclear test on Friday.

The B-1B bombers were moved to Andersen Air Force base in Guam in August as part of the policy of extended deterrence and a “Continuous Bomber Presence,” according to the U.S. Pacific Command.