An anti-Islamic protest in Houston held six months before the last US election saw extra police on the streets amid online threats of violence.

Organised by a Facebook group called Heart of Texas, it was billed as the "Stop Islamisation of Texas" rally and drew a counter protest by “United Muslims of America”.

However, while protesters on both sides turned up to shout "white power" and "stop the hate" at each other, the Facebook organisers were noticeably absent.

That was because they were more than 5,500 miles away in St Petersburg.

The incident was a stark example of how Russian trolls sowed division in the US in the build-up to the 2016 election, one of a number of tactics used to interfere in America's democracy.