You wouldn't need ICBMs in Mexico to target the US. That "C" in ICBM renders it MOOT, not Mute.
You could employ IRBMs.
Anyway, as one of the "children" around here, I fear this will not end well (duh) and Putin will eventually "win" unless he is pulled from office somehow. As I noted a while back, I think he loses a lot even if he "wins" militarily, and doesn't gain much of anything.
Ukraine is a poor country in GDP per capita, they do have natural resources, but so does Russia. Ukrainians won't be happy with whoever gets put "in charge".