Frank Gardner
Security correspondent

France has no shortage of adversaries when it comes to people who profoundly resent its government’s policies, over Ukraine, West Africa or closer to home, the wearing of the veil.

Over the past decade, the country has been the victim of several major attacks – in Paris, Nice and elsewhere, all linked to so-called Islamic State (Isis) – as well as smaller, isolated, but still violent attacks on individuals by jihadists.

Today’s attack on France’s high-speed rail network has been classed as sabotage, rather than terrorism – no-one was killed – so Isis and al-Qaeda are unlikely to be at the top of the list of suspects.

In April, French president Emmanuel Macron said he had no doubt that Moscow would try to disrupt the Olympic Games in some way.

Investigators will be focusing their attention on activists and known extremists, as well as any possible links to the Kremlin.

The announcement by the Paris prosecutor’s office of the severe penalties for those responsible will be intended, as much as anything, as a deterrent to discourage anyone tempted to carry out any similar acts of sabotage.