Two B-1B strategic bombers of the U.S. Air Force took part in an exercise with two ROK F-15K fighter jets over the Korean Peninsula, Tuesday, according to the Republic of Korea (ROK) Air Force.

“The B-1Bs plan to stay over the peninsula for about two to three hours,” Lt. Col. Kim Sung-duk, a public relations officer for the ROK Air Force, said at a press briefing, confirming the sortie.

The U.S. Pacific Air Forces also confirmed the dispatch of the B-1B Lancers, based at the Andersen Air Force Base, Guam, to the vicinity of the peninsula on its Facebook account.

“These flights with the Republic of Korea demonstrate solidarity between the ROK and U.S. to defend against provocative and destabilizing actions in the Pacific theater,” it said.

It is rare for the both militaries to confirm the details of operations involving U.S. strategic assets.

The rare disclosure was construed by some as the U.S. circuitously expressing its discontent over controversial remarks recently made by President Moon Jae-in’s special presidential adviser for unification, security and foreign affairs, Moon Chung-in.

During a Wilson Center seminar in Washington, Friday, the adviser suggested a willingness to reduce the scale of the allies’ military exercises and the frequency of the dispatch of strategic assets to the peninsula if North Korea suspends its nuclear and missile programs.

The latest dispatch of the Lancers also came after the death of Otto Warmbier, a 22-year-old U.S. college student released from the North last week in a coma after 17 months in detention.

Warmbier died Monday (local time), according to his family who claimed his death was due to the “torturous mistreatment… received at the hands of the North Koreans.”

Regarding the reason for the dispatch, Lt. Col. Kim said, “It is part of regular drills between South Korea and the U.S.”