*sigh*
First off - the evidence actually points to Air Traffic Control in Kiev diverting the flight that was shot down. The same flight had, over the prior 11 trips, been diverted well around that region.
Basically - ATC in the Ukraine had to instruct the plane to enter the air space and then instruct it to lower its altitude (as 37000 feet is far lower than it would normally be).
Even if it was Russian separatists who ultimately fired the missile - all evidence points to it being, at the least, a baiting by the Ukraine. Since the Ukrainian equivalent of the "Secret Service" immediately confiscated all recordings from the tower in Kiev - it's relatively suspicious (as that would have been the tower to divert the aircraft).
Anyway -
As for nuclear war - it's hardly the threat they make it out to be. Overpriced firecrackers is what nuclear weapons are. They have been illustrated time and time again to be underwhelming in terms of actual performance. Sure - they are terrifying weapons - but they are not nearly as effective as they are labeled to be.
It would take the world's nuclear arsenal to destroy a plot of land the size of my home state. The world is hardly in jeopardy from our meager attempts to destroy ourselves.
