[ThrowawayR2]

Let's analyze what it would take to make your scenario work: some state actor is going to fly a drone or aircraft with the range to reach the US (launched from where?), past any radars and other sensors that the continental US has without being detected (and then fly back out even), drop a specialized munition that leaves large, analyzable debris behind, and somehow not be identified to face reprisal. That is exceedingly unlikely.

[kipchak]

Why not just launch the drone from inside the US and use a generic explosive? Unexplained drone swarms near sensitive targets have been fairly common.[1,2] Them not being weaponized seems like more of a choice for reprisal like you said than a lack of capability.

[1]https://www.forbes.com/sites/davidhambling/2020/07/30/drone-...

[2]https://www.thedrive.com/the-war-zone/34662/faa-documents-of...