[stymaar]

> but you unwittingly engage them rather than them engaging you.

Directional anti-tank mines are a thing: https://en.wikipedia.org/wiki/PARM_1_mine

[dwd]

Or the Russian POM-3, scattered by aerial deployment, detects vibrations before bounding and detonating in the air.

https://en.wikipedia.org/wiki/POM-3_mine