Well, Kenedy was able to totally isolate Cuba and discuss it. NATO is at Russian doorsteps (assuming that Ukraine is entering), probably less than hour to reach Moscow by missiles deployed there. I do not think, Putin has too many options, but to invade Ukraine. And considering the firm stands of the Washington administration he can probably do that and get away with that. I don’t think, that the contingent can take over entire Ukraine (half of the eastern population speaks Russian anyway), but can “free” few “provinces” alongside the border just to make the point.