i also noticed it goes to pop 0 if it loses 1 man... So i see some call on a couple squads put them in harms way lose the 1 guy then sweep for mines.....
its because one man is worth 1 pop and the other is worth 0, hence the 1 pop unit. If the 1 pop guy dies the squad survives but has 0 pop, and vice versa should the 0 guy die.