Strictly speaking, the 1920s. Otherwise, 1991.
Are you high on something? You do realise that besides Americans there other people on this forum who know the history of this part of Europe, right?
It will come along with the deliveries of stuff too complex for the untrained z-holes to operate.
There isn't anything "too complex" for Ukrainian soldiers - if Americans can operate something, then the rest of humanity can do it too lol
Then the "advisors" will morph into US Marines and "advising" into a shooting war between said Marines and the Red Army.
I see you're stuck in the Cold War era - there's no Red Army anymore lol
And Ukrainians are being trained in NATO countries - Poland, Germany, the UK, so there's no need for US advisors to go to Ukraine.