July 17th Russian terrorists operating in Ukraine shot down a commercial boeing 777 thinking it was a Ukrainian transport aircraft AN-26.
Here are some videos of the plane crashing:
The reason why this happened is because Ukraine was trying to kick out the terrorists and soldiers Russia was sending into East-Ukraine using SU-25 fighter jets. Russia wants to do in Ukraine what it did in Crimea too: take over and annex large parts of it.
The (pro)Russian terrorists up untill last week had portable anti-air systems called MANPADs, but these are not very effective against jets. With air dominance the (pro)Russian terrorists where loosing a lot of ground. Therefore last week Russia was sending advanced air-defense systems into Ukraine to fend of the jets. These are so called BUK-M1 systems.
The Russians were bragging that they got such a system. After discovering their failure they removed all such messages, but the internet community has been able so save all. This is a tweet later deleted, that shows how the DNR brags about having a BUK (thanks to @RobPulseNews):
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