Still wasn't a US Military Action. It was a volunteer group.
So let's suppose a group of active-duty Saudi military officers were given official permission by their government to leave their military for the purpose of forming a group that would be conducting operations whose primary purpose was the killing of US citizens.
Let's also suppose they were given Saudi military arms, military planes, equiptment and supplies "on loan" for this purpose.
You would not consider their subsequent actions to be anything we should have a long talk with the Saudi government about?