The Malaysian aircraft destruction is tragic, but not unique. Commercial Airliners have been shot down before. In 1983 the Soviet air defense fighters shot down a Korean Airlines 747 that had strayed off course, impinged on Soviet airspace and the Soviet Air Defense presumably mistaking the aircraft for an American surveillance aircraft, downed it. The completely bungled the aftermath by denying it and then the US let on that we had collected all the communications and we went on to play them in the UN Security Council. (I happened to be the State Dept. analyst who accompanied Ambassador Jeanne Kirkpatrick during this Council meeting.)
The US mistakenly shot down an Iranian civilian Airbus (killing about 300) during the Iran Iraq war when the US was patrolling the Gulf to protect oil shipping. The USS Vincennes fired in error and it was a tragic disaster, but the US admitted it.
The Malaysian case will play out similar to the Korean incident. The Russians will not be so boneheaded and deny the event. What happened will be clear from intelligence sources and the investigation. What Russian and Ukraine will be doing is making responsibility as murky as possible. Intercepted communications will drive this.
One point that does stick out from the events of yesterday. The White House declared that President Obama learned of the event during a phone call with Vladimir Putin on Sanctions. This is amazing. The Intelligence Community, which has lots of technical collection in the area (recall we still watch for Russian nuclear missile launches to warn of sudden attack among other things) must have seen this virtually in real time…but for some reason, no one passed the word to the President? Maybe they thought he wouldn’t care? Maybe the message got tied up in the DNI bureaucracy? Maybe the White House staff held it up? Maybe they just dismissed it as a non-threat incident? There is a story there that would be interesting to read.