Friday's development follows an assessment by United States think tank 38 North that North Korea's Sohae Satellite Launch Facility, which had been partially disassembled as part of a pledge by Pyongyang leader Kim Jong-un, is now back to normal operational status after a flurry of restoration work in recent weeks.
A much anticipated meeting between the two leaders in the Vietnamese capital last week ended without a deal over differences in how much North Korea was willing to limit its nuclear programme before it was granted some sanction relief.
South Korean President Moon Jae-in has replaced his unification minister who played a major role in detente with North Korea over the past year, his office said on Friday, and named a longtime confidant to lead a drive for "a new Korean peninsula".
"The public at home and overseas. are feeling regretful, blaming the USA for the summit that ended without an agreement", an editorial published by KCNA wrote.
Following President Donald Trump's stalemate talks with Kim Jong-Un, it appears North Korea may be preparing to launch a missile or rocket some time soon.
Trump and Kim, who also met in Singapore previous year, have not said if there will be a third summit.
"The intent of the North Koreans in this matter is known only to them", he added.
The pictures show the location Sanumdong, a plant in the North Korea so far, ballistic missiles and rockets to Launch satellites has been tested.More news: Trump today: Paul Manafort jailed
Many experts think the lack of comprehensive joint exercises will eventually likely weaken the allies' military readiness if diplomacy fails and tensions with North Korea return.
The North Koreans put a smaller - relatively smaller deal on the table that experts we talk to say was meant to be a starting point.
After leaving the conference The Donald said: "The one thing we have, though, is we have no testing, no missiles going up, no rockets going up, no nuclear testing".
Trump administration officials have long vowed to keep up economic pressure until the North takes credible steps towards the peninsula's complete denuclearization.
New activity has been detected at a factory that produced North Korea's first intercontinental ballistic missiles (ICBMs) capable of reaching the United States, South Korea's JoongAng Ilbo and Donga Ilbo newspapers reported, citing lawmakers briefed by the National Intelligence Service. Undeterred by the breakdown of the Trump-Kim summit, South Korea has continued to urge the United States to ease sanctions on North Korea to allow a resumption of inter-Korean economic projects and encourage more disarmament steps from the North.
North Korea has frozen nuclear and missile testing since 2017, and Trump has pointed to this as a positive outcome from almost a year of high-level engagement with North Korea. It also became clear that Kim's hopes of faking denuclearization to get the worldwide community to ease sanctions have failed.