One evening in February, as Ivan Gorlovko was burying his dog in the frozen yard behind his house in Chuhuiv, 25 miles south-east of Kharkiv, he heard a screech of tyres and looked up to see a convoy of Ukrainian army trucks on the bridge over the Siverskyi Donets. The link between Laika’s death and the military vehicles on the bridge was not accidental as far as Gorlovko was concerned. He was sure the trucks belonged to the Security Service of Ukraine and were transporting dangerous pathogens from the Chuhuiv Bacteriological Institute to a place of safety in the west of Ukraine in case of a Russian invasion.