At that time, the airspace was closed over the area up to 32,000 feet. The commercial flight MH17 was passing the area at 33,000 feet. There was nothing to suggest at the time that the presumed ill-equipped pro-Russian separatists would have access to sophisticated weapons that would be able to shoot down an airplane at that height.
The international rules on regarding airspace over conflict zones, signatories to the Convention on International Civil Aviation (Chicago Convention), ICAO Member States are obliged to promptly communicate potential risks to safe and secure civil aviation operations in their sovereign or delegated airspace, including those relating to conflict zones. This had been done, and many airlines, including Lufthansa and Air France-KLM, sent their jets over eastern Ukraine until the MH17 crash www.ft.com/content/388331f4-1249-11e4-93a5-00144feabdc0,
The Joint Investigation Team investigation has meticulously traced the BUK that shot down MH17 on its way from Russia and back. For a full explanation of the findings from the JIT, watch their video where they conclude that the BUK that shot down MH17 came from the Russian Armed Forces. It was transported into pro-Russian separatist controlled area by a Russian convoy. There is forensic and visual evidence, and three independent investigations have all come to the same conclusion. Meanwhile, Russia used its veto to block a draft resolution to set up an international tribunal into the MH17 air disaster.