I presume the announcement about the pipeline bombing is intended to be equivalent to "They have found no conclusive evidence to tie any actor to the explosion." I wish it were stated that way so it was clear.
Other things that could be found:
1) There are many/few actors that could have achieved this explosion. (I suspect it takes more than some drunk teenagers thinking it would be a good idea.)
2) The known Russian (or other actor) units that might have done this were known to be elsewhere and can be ruled out.
3) There was or was not evidence of concealment that requires a capability accessible to a few actors.
Remember that lack of evidence can be evidence. If bombs drop from the sky but your radar shows no planes, that's evidence of stealth technology.
To me, this attack, and the failure to find a perpetrator, indicates a serious defense weakness in Europe. I worry where the US has similar weaknesses. I would have to believe this incident is serving as an alert for these weaknesses to be dealt with.
Other things that could be found:
1) There are many/few actors that could have achieved this explosion. (I suspect it takes more than some drunk teenagers thinking it would be a good idea.)
2) The known Russian (or other actor) units that might have done this were known to be elsewhere and can be ruled out.
3) There was or was not evidence of concealment that requires a capability accessible to a few actors.
Remember that lack of evidence can be evidence. If bombs drop from the sky but your radar shows no planes, that's evidence of stealth technology.
To me, this attack, and the failure to find a perpetrator, indicates a serious defense weakness in Europe. I worry where the US has similar weaknesses. I would have to believe this incident is serving as an alert for these weaknesses to be dealt with.