How would the U.S. react if Mexico entered into a military alliance with China? Then started letting China build military bases and surveillance platforms in Northern Mexico?
Then lets say that a drug cartel got really out of control (who was getting their chemicals from rogue Chinese companies while other Chinese actors - possibly even Chinese intelligence washed their money) and was armed to the teeth and was murdering all kinds of people on both sides of the border while funneling tons of illegal drugs into the United States distributed across a vast network of cartel member/gangs in U.S. cities. The U.S. wants to cut off the head of the snake, but an attack on Mexico, even a drug lord compound is considered by the Chinese, to also be an attack on China.
Well, we'd absolutely lose our crap right from the start of any such overtures between Mexico and China.
So why is anyone the least bit surprised that Russia is reacting they way they are?