Human Rights Watch :

Customary international humanitarian lawprohibits the use of booby traps – objects that civilians are likely to be attracted to or are associated with normal civilian daily use – precisely to avoid putting civilians at grave risk and produce the devastating scenes that continue to unfold across Lebanon today. The use of an explosive device whose exact location could not be reliably known would be unlawfully indiscriminate, using a means of attack that could not be directed at a specific military target and as a result would strike military targets and civilians without distinction.