I heard there's methods of laying mines whereby its close to almost impossible to remove the mine.
1 method is 4AP mines, 3 of them in a closed triangle formation while the 4th one is under all 3 of the mines. This way, if you tried to remove the any of the 3 top AP mine, the 4th one below the 3 AP mines will trigger and explode. So how do you disarm it? Only way, I see it is by using a C4 charge.
2 method is 2 AP mines, 1AP mine on top, while the other is below, the trick is the type of AP mine used below...
There are so many of these methods out there, I really sympathize our engineers who have to 'dig' and search and disarm the mine... if they encounter of any these methods, they're dead!