At some point after 27 September, the CIA had added to its X profile page a link - https://t.me/securelycontactingcia - to its Telegram channel containing information about contacting the organisation on the dark net and through other secretive means.

The channel said, in Russian: “Our global mission demands that individuals be able to reach out to CIA securely from anywhere,” while warning potential recruits to “be wary of any channels that claim to represent the CIA”.

But a flaw in how X displays some links meant the full web address had been truncated to https://t.me/securelycont - an unused Telegram username.

As soon as Mr McSheehan noticed the issue, he registered the username so anyone clicking on the link was directed to his own channel, which warned them not to share any secret or sensitive information.

It’s high time for any US government agencies to leave Twitter