North Korea was seen mobilising warplanes and bolstering its coastal defence system after the US forces flew its bombers in the Korean peninsula, warned South Korea's top spy agency. Pyongyang's move in recalibrating its weapons was seen a direct response to Washington's latest manoeuvre in flying the sophisticated B-1B bombers.

On Saturday, 23 September, the US flew B-1B Lancer bombers from its Anderson Air Force Base in Guam and they were escorted by F-15 fighters from the Japan base. It was a rare operation as the flights cruised closer to North Korean territory, but they were in international airspace throughout. Pyongyang is in possession of radar systems, which are capable of detecting planes within a range of 600kms.

In the latest, South Korea's National Intelligence Service (NIS) told a parliamentary briefing that Pyongyang was seen readjusting its weapons system.

Lee Cheol-woo, chief of parliament's key intelligence committee, said the readjustment was due to the fact that North Korea could not even detect the latest flight made by the US bombers. "We (lawmakers) heard (from the NIS) that as the flight was close to midnight, the North might not have anticipated it at all, or the North might have been unable to take action as not have or other systems could not clearly detect," said Lee.

The revelation comes amid North Korea's threats to shoot down Washington's bombers, claiming the US has already declared a war on the Kim Jong-un regime. War of words between the US and North Korea escalated over the past few weeks, with both sides refusing to scale down any of their warnings.

Meanwhile, the White House has rejected assertions made by North Korean foreign minister that the US has declared a war on his country. Calling remarks by North Korea "absurd", White House spokesperson Sarah Sanders said: "It's never appropriate for a country to shoot down another country's aircraft when it's over international waters. Our goal is still the same. We continue to seek the peaceful denuclearization of the Korean peninsula."

US B1-B bombers
Two US Air Force B-1B Lancer bombers fly from Andersen Air Force Base, Guam, for a 10-hour mission, with an escort of a pair of Japan Self-Defense Forces F-2 fighter jets in the vicinity of Kyushu, Japan US Air Force/Handout via Reuters