North Korea Reportedly Laying Landmines on the Chinese Border to Keep Out Coronavirus
These landmines could just as easily be used to keep people in than keeping people out:

North Korea has taken extreme measures to fend off the coronavirus, including laying landmines in border areas with China, Seoul’s National Intelligence Service (NIS) told lawmakers Tuesday.
During a closed-door session at the Intelligence Committee of the National Assembly, the spy agency said North Korea fears the spread of COVID-19 could bring catastrophic results to the country due to its poor medical infrastructure, according to Rep. Ha Tae-keung of the main opposition People Power Party.
“Since there is no physical or technical means to deal with the coronavirus, there is something like coronavirus trauma in North Korea,” Ha quoted the NIS as saying.
Yonhap
You can read more at the link.

