[coconut_crab]

Vietnam formed a task force called GK1 to research how to safely detonate those mines during the war. According to them the mines at Hòn La were detonated due to lightning stroke nearby.

Source: all 11 members of GK1 were from my university. I still remember the first day at school and they were talking about how they provided engineering effort for the war (bazooka clone, sea mines clearance, 2nd Mig pilot to downed a B52 etc..) but I'm sure some of them are just propaganda.