I was in China back in 1990 while the college I was working for was trying to establish exchanges with educational institutions there.
At one school in Chongqing, we meet some North Koreans, who had been sent to Chongqing to study...English.
I guess their government was so paranoid about ideological contamination that it didn't dare send anyone to a real English-speaking country. Perhaps they thought it was dangerous enough that the school in Chongqing had teachers from Australia.