A North Korea missile launch (Picture: PA).
North Korea is reportedly restoring facilities at its long-range rocket launch site that it had dismantled as part of disarmament steps last year.
The development came after talks over denuclearisation of the Korean Peninsular between North Korean leader Kim Jong Un and US President Donald Trump ended without any agreement.
Images taken by commercial satellites were posted in an article by 38 North, a website specialising in North Korea studies.
The images reportedly show efforts being taken to rebuild some of the structures at the Tongchang-ri launch site.
The images were taken just two days after talks between the two leaders collapsed in Hanoi, Vietnam.
It is believed that the rebuilding work began sometime between 16 February and 2 March.
The site is where North Korea carried out satellite launches in recent years, inviting rounds of sanctions from the UN that saw it as a disguised test of missile technology.
South Korea's JoongAng Ilbo newspaper reported that the country's spy service also gave such an assessment on the site in a private briefing on Tuesday.
JoongAng Ilbo cited unidentified politicians who attended the briefing as saying that National Intelligence Service director Suh Hoon told them that the structures being restored at the launch site include roofs and doors of buildings.
Mr Suh was quoted as saying that the move is seen as a preparation to restart long-range missile test-launches in the event that talks over denuclearisation collapse.
He also reportedly said the rebuilding of some structures was to blow up the launch site more dramatically as a sign of commitment to denuclearisation if the talks had gone well.
The offices of South Korean politicians who took part in Tuesday's briefing could not immediately confirm the newspaper report.
The 38 North report said the rail-mounted transfer building is being reassembled at the launch site.
It said two support cranes can be seen at the building, and walls have been erected and a new roof added.
At the engine test stand, the website said it appears that the engine support structure is being reassembled.
It said new roofs have been installed on the fuel and oxidiser buildings.