Movement of cargo vehicles also spotted recently around an intercontinental ballistic missile plant, news reports say.
North Korea has attacked the ongoing joint military exercises between Seoul and Washington as an “open challenge” to the efforts towards peace on the Korean Peninsula.
On Saturday, the US and South Korea agreed to replace two major annual war games – the Key Resolve and Foal Eagle drills – with a shorter “Dong Maeng” or “Alliance” exercise which kicked off this week.
The move was designed to further ease tensions with Pyongyang following the dramatic detente since early 2018.
“The ill-boding moves of the South Korean military authorities and the US are a wanton violation of the DPRK-US joint statement [in Singapore] and the North-South declarations in which the removal of hostility and tensions were committed to,” the North’s official news agency, KCNA, said.
There are almost 28,500 US troops stationed in South Korea, and their annual drills with tens of thousands of South Korean soldiers have always infuriated North Korea – with Pyongyang condemning the manoeuvres as provocative rehearsals for invasion.
However, following the first meeting between US President Donald Trump and North Korean leader Kim Jong Un in Singapore last year, Trump raised eyebrows at a press conference when he said Washington would suspend the “very provocative” US joint military exercises with South Korea.
The two leaders also signed a vaguely worded pledge on denuclearisation of the Korean Peninsula.
It is unclear what “violation” of that pledge North Korea was referencing in its statement.
The flare-up comes just days after Trump and Kim held a second summit, this time in Vietnam, but talks concluded early with no progress towards Washington’s goal of getting North Korea to give up its nuclear weapons.
Following the stalemate, researchers said this week that Pyongyang was rebuilding the Sohae long-range rocket site after Kim had agreed last year to shut it as part of confidence-building measures.
On Thursday, US experts said the missile launch site was ‘operational’ again.
Movement of cargo vehicles was spotted recently around a factory at Sanumdong in the capital Pyongyang, which produced North Korea’s first intercontinental ballistic missile capable of reaching the United States, South Korea’s JoongAng Ilbo and Donga Ilbo newspapers reported, citing legislators briefed by the National Intelligence Service (NIS).
JoongAng Ilbo also quoted Suh as saying North Korea continued to operate its uranium-enrichment facility at the main Yongbyon nuclear complex. But that contradicted reports from a day earlier that no activity was ongoing there since late last year, concurring with findings from the UN atomic watchdog.
Trump said he would be “very, very disappointed” if the reports proved true.
Joel Wit, a North Korea proliferation expert who helped negotiate with North Korea in the mid-1990s, said the Sohae reports are Kim’s way of showing he’s “getting impatient with lack of progress in negotiations”.
“We have to watch to see what else happens,” Wit said. “It’s a space launch facility and has been used to send satellites into space … Problem is some of the technologies [with rockets] are the same.”