Who could be behind hoax bomb threats to European air travel?

The warnings came in thick and fast, targeting one airline or airport after another.

In nearly all cases - London's Heathrow airport being a notable exception - they were taken to be credible enough to divert the aircraft in question, or even in Italy's case, to scramble fighter jets to escort it.

They all turned out to be false, which does not, of course, mean that the next ones will not be real.

It is hardly surprising that the simultaneous, co-ordinated nature of these airline hoaxes, coupled with other malicious actions across Europe, are causing some people to point the finger of suspicion at Russia.