Once upon a time, bank robbers wore balaclavas and dug tunnels. No longer. Three months ago, the world experienced the biggest bank robbery in history when thieves stole $101m from the central bank of Bangladesh.

But these 21st-century fraudsters did not use guns; instead they acquired the access code for the global cross-border bank payment messaging system known as Swift, and used these to persuade the US Federal Reserve to transfer money to their accounts. Then they tampered with the banks’ software to erase their cyber fingerprints.

That is alarming. More worrying still, this is not an isolated heist. This week Swift officials confirmed that a Vietnamese bank suffered a similar attack six months ago when robbers tried (and happily failed) to take more than $1m.