Well, if you don’t want a bridge to be used, you can either mine it, or tear it down. The latter is a lot more work, and you can’t exactly only tear down your half of it.

The Geneva convention is fine with landmines. The Ottawa treaty band anti-personel mines, but it does not ban anti-vehicle or anti-armor mines. The logic being that if you don’t set it off by stepping it, it’s not that big a risk.

Now, I’m not a mine expert, but these ones look WAY too big to be anything but antitank mines.