[gpm]

Why domestic? The US isn't lacking in international adversaries that would be interested in the ability to execute low cost attacks against critical infrastructure.

If it was domestic terrorists it seems likely they would have seized the opportunity to do damage immediately instead of showing their hand like this. An "advanced persistent threat" (such as a foreign country) to borrow from the computer security world seems more likely to take this sort of "test but don't actually damage anything" approach.

[bilbo0s]

Foreign states have the resources to build their own field tests.

But time will tell. In fact it already has. We just need to wait for the investigation to complete.

My own money would be on a terrorist organization. A bit less certain that it would be domestic, but domestic is still more probable than foreign in my mind. The past few years, and the past year in particular, has shown me that our domestic terrorists on the left and the right are bat$#!t crazy.

But as I said, we'll see.

[jvanderbot]

I suppose I mis-spoke. Could easily be a domestic ally of a foreign adversary.