Speculation among some high-ranking Nato officials was that Vladimir Putin, the Russian president, could send his forces over the border during August – ahead of a planned summit of NATO leaders in September. Moscow chose the summer lull – and the diversion of the Beijing Olympics – to march into Georgia in 2008 in support of secessionists in South Ossetia.

Another theory had it that Mr Putin might wait until September when marching over the Ukrainian border, as he had done in Crimea, would be seen as a defiant response to the alliance meeting. Nato leaders are expected to use their gathering in Newport, Wales, to bolster the defences of members in the eastern half of the continent – a move certain to draw angry protests from Moscow.

Either way, Russian officials and diplomats have been busy laying the propaganda groundwork for such an invasion. They have been warning that fierce fighting between the rebels – guided and supplied, of course, by Moscow – and the Ukrainian army threatens a human disaster, with civilians deprived during the winter of the basic requirements of food and fuel. It was easy to see where this was going: a direct invasion by Russian forces would be framed by the Kremlin as a humanitarian exercise to safeguard innocent civilians.