They were volunteers.
Not "trainers" not "advisors".
Volunteers. Chose to fight the Russian expansion by aggression because they believe in democracy (and abhor bullies).
Yeah the longer this goes on I'm certain you will see more American volunteers in Ukraine. God speed to all of them.
Let's not speculate that the US has some sort of clandestine troop deployment to Ukraine. That detracts from what these guys stood for imo.