Photographs from high above North Korea show what observers say are concerning developments in the regime's arsenal of repression.
Amnesty International has published a series of images above two prison camps known as Kwanliso 15 and Kwanliso 25.
They're taken from the same position as 2013 images and show identical infrastructure, but there are a few minor differences. One in particular is of the most concern.
There are new guard posts and agricultural work is continuing at the camps where the UN previously documented rape, infanticide, torture, starvation and executions of up to 120,000 men, women and children.
But there's also movement around what's believed to be a crematorium.
In a new report, Amnesty wrote the "reported crematory ... appears to have undergone changes with a new roof and possibly the entire structure".
A new guard post appears to have been positioned near the entrance to the structure.
News.com.au reported in 2013 that the prison camps house more than 50,000 prisoners in conditions deemed inhuman by the rest of the world.
At the time, Kwanliso's population appeared to be expanding and new housing blocks were visible.
The latest report shines light on a region concerned parties remain banned from accessing.
Micah Farfour, Amnesty International's imagery analyst, said: "Taken together, the imagery we've analysed is consistent with our prior findings of forced labour and detention in North Korea's Kwanliso, and the physical infrastructure the government uses to commit atrocities are in working order.
"North Korea has consistently denied access to human rights observers, researchers, and others, hampering investigation into the abuses committed in the camps and the rest of the country.
However, the infrastructure required to commit the abuses documented by Amnesty International, the Commission, and others is so massive as to be observable from space."
He said over the period from December 2014 to August 2016, agricultural activities remained noticeable throughout the camp.
"The razing of 29 agricultural or industrial support buildings were observed over the same time period, as was the deconstruction of 14 prisoner housing units. Administrative buildings, guard posts, and fenced perimeters were maintained in the observed area of the examination period, which leads to conclusion that Prison Camp 15 is still functioning as a detention facility."
Former prison camp officials and detainees previously revealed what life was like in camps under North Korea's repressive leadership.
An official known as Mr Lee, who worked at one of the camps in the 1980s and 1990s, told Amnesty of just one brutal way guards executed prisoners.
He said detainees were forced to dig their own graves and were then killed with hammer blows to their necks. He also witnessed prison officers strangling detainees and then beating them to death with wooden sticks.
He said it was not uncommon for female inmates to simply disappear after being sexually assaulted.
"After a night of 'servicing' the officials, the women had to die because the secret could not get out," Mr Lee said. "This happens at most of the political prison camps."
Kim Young-soon, a former detainee in Camp 15 between 1980 and 1989, witnessed the deaths of two detainees who were caught attempting to escape.
"They were brought to a stage after they were badly beaten," she said.
"The prisoners were tied to wooden stakes and shot three times in their head, chest and feet."
North Korea has long dismissed reports the country had hosted mass political camps. Andrew Beswick from Amnesty Australia told said in 2013 that Pyongyang can no play the innocence card.
"With satellite technology and testimonies from former prisoners, their existence is not only undeniable, but shows they're still growing in size," he said.
"These camps may be hidden away, but new technologies mean that authorities can no longer deny the existence of these oppressive prison camps."