Days after photos leaked of a fire at one of North Korea's biggest and best-known hotels, the country has begun restricting access to Instagram.
On Monday, attempts to connect to Instagram's website via PC or smartphone were met with a message saying the site was on an Internet block list, according to an Associated Press reporter in Pyongyang.
"Warning! You can't connect to this website because it's in blacklist site," the warning read in English, according to the AP. The problems began about five days ago, it said.
While Internet access is impossible for all but a handful of the country's 25 million people, foreigners have enjoyed Internet access through cellular connections for just over two years. In contrast to the draconian censorship imposed on its own people, the Internet connection has been notable for being completely uncensored, even allowing access to sites that neighboring China routinely bans.
But the uncontrolled access may be a thing of the past.
The Instagram block is the first known example of active filtering in the country, although like much in North Korea, it's unclear why it happened.
It comes after the country tried to prevent photographs of the June 11 fire at the Koryo Hotel from reaching a wide audience. When a footbridge connecting the two towers of the hotel caught fire, security agents attempted to stop anyone taking photographs of the building, according to Reuters.
But the photos got out and within hours news of the hotel fire was in the headlines around the world.
A day later, the country suspended mobile Internet service.
The mobile Internet service returned last week and it appears the Instagram block began at around the same time.
North Korea's government typically covers up any example of failure in the country and indeed the fire has yet to be mentioned on state media services. The photographs represented a double threat: an impact to the country's image overseas from pictures of the iconic hotel ablaze and, perhaps more seriously, to the government's image inside the country if those photographs leaked back in.
With the block, the country joins neighboring South Korea in active filtering of the Internet.
South of the border, the government filters out sites associated with pornography and gambling and also prevents users from accessing all North Korean websites and those that are judged to praise the country and spread its propaganda.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is email@example.com