The US in the Ukraine

Open Email to:
Rep. Ed Royce, Chairman of the House Foreign Affairs Committee. 
Sen. Robert Menendez, Chairman of the Senate Committee on Foreign Relations.

Dear Rep. Royce and Sen. Menendez,
The US war drums continue beating to raise public interest in doing "something" in the Ukraine. John McCain is up to his usual warmonger rhetoric.
Before we go off half cocked, let's look at when the shoe would be on the other foot.
Ukraine is a neighbor of Russia, just as Mexico is a neighbor of the US.
Let's suppose Mexico comes into a state of semi-revolt, wherein the Mexican government wants to maintain ties with the US, but a large segment of rebels want to establish ties with Russia. Chances are the US would quickly supply money and arms to the Mexican government to control the rebels, and might even supply soldiers.
The Russians have only done that with the Ukraine government. Is that unreasonable, and does that justify our waving a war flag at the Russians?