It's been described as a frozen conflict but Ukraine's civil war has suddenly heated up. So why now? Some point to the flare-up following the first phone call between Donald Trump and Vladimir Putin. Is Moscow testing the West's resolve, or - as pro-Kremlin media suggest - did Kiev trigger the fighting to rally support in Washington?

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The P4 laboratory, on the campus of the Wuhan Institute of Virology, in Wuhan, in China's central Hubei province. (Hector Retamal/AFP via Getty Images)