“I have been claiming for a while that the US secretly had military folks on the ground in the Ukraine.”
Prior to the recent war by Russia there were several hundred Americans in Ukraine teaching and training Ukrainian forces on how to kill invading Russians. Seems the Ukrainians are good students.
In any case when Biden ordered American military advisors out of Ukraine on February 12th those who were under orders (active duty) did so. Some who were private contractors did not, as they were free to do so.