Russia is on the physical border of the Ukraine and proximity matters, just as the USA is way far away on the opposite side of the planet.
If Russia was trying to stir up hostilities in Mexico then the USA has a vested interest with our own neighboring Country.
Whatever happens in the Ukraine is rightfully the business of Russia and absolutely NOTHING will change that glaring reality.
To do so is outrageous, and Russia is correct to react with military force and I am certain that Russia will escalate to the maximum - and rightly so.
When the USA had our neighboring Country of Cuba making its alliance with the USSR then the USA threatened nuclear war under the terms of mutual assured destruction.
If America doubts the resolve of Russia in the Ukraine then we are playing a fool who could get us all killed in lightning speed.