In 1997 the US signed a deal (not ratified as a treaty by either side): NATO - Russia Founding Act.
http://www.nato.int/cps/en/natolive/official_texts_25468.htm
NATO agreed to not deploy nukes or combat troops to any of the old Warsaw Pact countries other than what these countries had indigenously...to assuage fierce Russian resistance to the expansion of NATO.
We have now moved Air assets and a small contingent of combat troops into Poland and are talking about a small exercise in Ukraine.
I don't believe Russia will be as sanguine as you are over this matter. In fact they may overtly drive tanks into the heart of Kiev and forcibly expel those troops.
What then?
I am sure you would be celebrating that event, but those few troops will be near the Polish border.
The Evil Empire is back and the sooner people recognize this, the better off we will all be.