They are in fact referencing project 596, which was a nuclear test conducted in a very remote desert region called "Lop Nur". This region was chosen because it is just over 300km away from the nearest town.
Meanwhile, the American Nevada test site was located only 65km away from the nearest town, and the USA remains the only country to have dropped a nuclear bomb directly on a civilian population, and they did it twice. (not even including the times they dropped nukes on small island populations, promising they'd be able to return.)
Every time a new country appeared at the top, I instinctively looked at its spot on the map to see the explosion - but I shouldn't have done that because the UK and France did all of their testing on their colonies.