Hangzhou China Sighting
Video and images of questionable provenance depicted objects in the sky over Hangzhou, China, in July 2010. The most likely explanation of this incident is a Chinese ballistic missile, the DF-21, or a Progress-M launch from Baikonur.
These videos and images circulated widely on the internet and in the mainstream press starting in July, 2010, even being reported in the English version of China Daily.
Subsequently, numerous earthly explanations of the video have emerged. Most notably, Geoff Forden in the Arms Control Wonk blog wrote a cogent - though he admits not as thorough as he could have written - analysis and explanation of this event, dated July 12, 2010. He concludes that it's most likely a Chinese DF-21 ballistic missile. In a follow up note on the blog post, he amends his assessment, and concludes that it's "almost certainly a Progress-M launch from Biakonur."
Others have debated the location and date of the widely circulated video and claimed the video was from Kazakhstan in late June 2010.