The oligarchs would "own" the armed forces if they were simply mindless automatons, with no thoughts or deeply held convictions and allegiances of their own.
Thankfully, that's not the case. The vast majority of our military people are of the people, and would stand with us, should a tyrannical government attempt to use them to overcome us through force.
Obviously I have no basis to argue the point, except to say that I do not underestimate the power of propaganda to sway the minds of service people to justify attacking their own countrymen. I hope you are right.