South Korea and the United States have also been conducting annual joint military exercises, which the North routinely criticises as a prelude to invasion.
“It is a situation where a lot of (military) exercise equipment is amassed in North Korea and also a lot of strategic assets are situated on the Korean peninsula because of the South Korea-U.S. military drills,” Lee told a briefing.
“We are closely watching the situation and will not be letting our guards down,” Lee said.
U.S. President Donald Trump praised Chinese efforts to rein in “the menace of North Korea” on Thursday, after North Korean state media warned the United States of a “super-mighty preemptive strike”.
Trump told a news conference “some very unusual moves have been made over the last two or three hours”, and that he was confident Chinese President Xi Jinping would “try very hard” to pressure Beijing’s neighbour North Korea over its nuclear and missile programmes.
Trump gave no indication of what the moves might be. None of the U.S. officials who told Reuters about the heightened level of activity by Chinese bombers suggested alarm or signalled that they knew the precise reason for such activity.
An official Chinese newspaper said on Friday there was optimism about persuading the North to end its pursuit of a nuclear programme without the use of force, “now that even the once tough-talking Donald Trump is onboard for a peaceful solution”.