Here is an excellent and HN-worthy writeup of the argument for legality, and the counterargument that it was an improper booby trap.[1] It seems to me most of the polarizarion on this board could have been avoided had the original article recognized (as does the one linked here) "that the legality or illegality of the pagers attack can only be determined on the basis of a detailed factual analysis and that the relevant facts are still not fully known."

I disagree with @dang's decision to leave the original link up, as it is nearly valuless in framing this discussion.

[1] https://lieber.westpoint.edu/well-it-depends-explosive-pager...