alt Hacker NewsA certain percent will fail to detonate automatically, so the area will still be unsafe for decades (or longer). Same issue with cluster munitions and high intensity bombing.
Hopefully they are treating these as a quickly deployable defense of last resort and not deploying them in advance. Mines can be deployed by special artillery shells and drones, but generally they shouldn’t be, ever.
No point in deploying them in advance. Finland has proper winters and with the freezing/thawing cycle, the mines would end up god knows where. I myself once discovered an unexploded WWII aerial bomb that popped up out of nowhere one spring on a field that was in constant farming use.