More likely a sub.
Consider, instead, the recent (last 75 years) history of Argentina, notable immigrants to that country, and the facility with submersibles those immigrants had when they arrived.
More or less. It probably isn't that complicated. Just target the right mentally disturbed individuals, prime them properly, and then give them the impetus and incentive to act. Along with the psychoactive meds.
He's trying to shift the narrative by making this an issue of "gun safety", not "gun control", because the latter has such a high negative index.
Next, watch them try to push the "school safety" narrative, pointing out that schools seem to attract these things. They will howl about unsafe campuses.
To counter, point out that the real danger to students, sexually predatory teachers and admin, have been humping our kids for decades without real accountability, and you haven't done anything about it . . . why are you worried about this?