This is a shocking story, the US strike killed up to 100 pro-regime forces. I mean, that’s a lot, the pro-regime could mean anything from Syrian footsoldiers to Russian advisors, Iranians, Hezbollah and so on. This is really something to watch and I already watch the situation like a hawk. Who knows where this could lead. OTOH, it does seem the troops were provoking something.
Agree or not, the top-brass is obviously, running this show. To be a fly on the wall. I look at various websites, “long war journal”, etc. Intriguing situation.
Perhaps Russian Mercenaries hit per CBS:
https://www.cbsnews.com/news/forces-hit-by-u-s-in-syria-included-russian-mercenaries-official-says/
More: http://www.middleeasteye.net/news/us-led-strikes-syria-pro-government-forces-kill-100-us-official-1924957295 (Image of Coalition Joint Task force document)