North Korea on Thursday accused the United States of flying a nuclear-capable bomber over South Korea and said the event could imperil regional stability.
Pyongyang's powerful National Defense Commission said the B-52 practice sortie occurred on Wednesday off the west coast of the Korean Peninsula, Reuters reported.
The North for weeks has been warning the United States not to involve nuclear-capable aircraft in its drills with South Korea. When B-2 and B-52 planes conducted a bombing exercise over the South last spring, the event played a big role in contributing to high tensions with Pyongyang.
An anonymous South Korea defense insider told the Yonhap News Agency that only one U.S. nuclear-ready aircraft participated in the Wednesday drill.
A U.S. armed forces spokeswoman declined to discuss the matter, saying: "The U.S. Pacific Command has maintained a rotational strategic bomber presence in the region for more than a decade."
The North's National Defense Commission spokesman accused Seoul and Washington of preparing to carry out a nuclear strike: "At the time when the [South Korea-North Korea] agreement was made on reunions of separated families and relatives at Panmunjom, a formation of U.S. B-52 strategic bombers from Guam was carrying out nuclear strike practices all day over Korea's west sea, aiming at us."
Hazel Smith, a U.K.-based North Korea analyst, predicted that Pyongyang would retaliate in some way: "Since North Korea is motivated by military thinking, a show of force is probably going to provoke a response."
Upcoming U.S.-South Korea armed forces maneuvers will for the first time involve the two allies' recently completed tailored strategy on extended nuclear deterrence, Yonhap reported.
The bilateral strategy includes plans for responding to a range of North Korean nuclear threats.
The U.S. and South Korean militaries will incorporate a variety of atomic-emergency situations in this spring's joint exercises, the South Korean Defense Ministry said. South Korean and U.S. officials will use the outcomes from the nuclear scenario drills to flesh out the specifics of their deterrence strategy by the end of 2014.
The two countries will increase further their surveillance of North Korea's strategic assets including nuclear and missile sites. Additionally, the U.S. and South Korean militaries plan to stage exercises in August designed to test their readiness for responding to a biological or chemical strike.
"We will prepare for both provocations and an all-out-war and establish deterrence posture against any provocations by the enemy," South Korean Defense Minister Kim Kwan-jin said in a yearly policy update to the president.