Sitting here in the peaceful countryside in the middle of America, it seems remote and unlikely, even ridiculous. The Soviet Union's shoot-down of a Korean airliner with an American Congressman aboard occurred at an especially tense juncture in the Cold War but resulted in little other than tough talk -- partly because the KLA 007 was off-course over Kamchatka. Similarly, a few years later when the USS Vincennes shot down an Iranian passenger airliner, Flight 655, over Iranian territorial waters, there was much justified criticism and many recriminations but no war.
The trouble with black swans is that you don't know you are expecting one until you see it. What would the world be like with missiles falling on American cities and a billion fewer people? We don't even want to think about it.
As horrible as this incident is, regardless of the identity or motives of the perpetrators, we should not allow ourselves to be orated into any kind of armed conflict over it. MH17 was flying in range of, if not directly over, a war zone -- a potentially dangerous decision. Some evidence seems to suggest that it took an flight path other than the normal one. It's hard to see how anyone could benefit from taking down a civilian airliner on its way to Kuala Lumpur from the Netherlands, and it seems reasonable to assume this was a tragic accident, with the airliner perhaps being mistaken for a Ukrainian government transport plane by separatist rebels with communications equipment not equal to their firepower.
We need to keep our eyes on the ball. I would suggest that before we start worrying about the Ukraine, we shut down the IRS and seal the southern border. I guess we could seal the Canadian border, too, so we're not accused of being directionists. (Imagine the horror of tens of guys named Brian and Edward pouring south into Minnesota and lining up to get henna tattoos at a Mall of America kiosk. Perhaps worse, from the Canadian side, imagine a couple a hundred Lutheran Scandahoovians jumpin' the border into that there Ontario place to sample the swinging night life.)
P.S. And another thing: the CIA, supposedly, based on images captured by one of their satellites, was able to see the flash of the missile striking the plane, and they claim to have tracked the path of the SAM back to it's launch location near the Russian border. They are also fairly certain about the type of missile it was. Yet they can't recover Lois Lerner's emails?