MEANWHILE,

President Hollande launched reprisals against IS last night, mounting revenge raids on jihadi targets. There have also been renewed calls to allow British warplanes – already deployed in Iraq – to bomb Syria.

Such a desire for retribution is understandable but we know from bitter experience in Iraq, Afghanistan and Libya that ill-considered military action can have catastrophic consequences.

And in any case, America, Russia and France are already bombing every known IS target in Syria, so British involvement would be little more than symbolic.

Far better than simply raining down more bombs would be to develop a coherent strategy for exterminating IS and bringing peace to the region. This would involve Nato allies in some unpalatable negotiations with Iran, Russia and even the Assad regime in Damascus – which until recently Mr Cameron wanted to bomb.

The threat from IS is so deadly that old enmities must be set aside until it is eliminated. But the overriding question is how best to keep people safe at home? The security services have been remarkably successful at protecting Britain over the past decade but the risks grow daily.

The revelations of CIA traitor Edward Snowden about security service surveillance techniques have made it much easier for terrorists to communicate under the radar, which is why Theresa May’s enhanced powers for British agents to intercept private electronic communications are needed – albeit under carefully regulated conditions.

The Islamic community also has a vital role to play in identifying the radicals in its midst. But we should never forget that the vast majority of Muslims are as appalled by the medieval barbarism of IS as anyone and desperately want to see it crushed.

Central to the IS strategy is to sow division – to pit Muslim against non-Muslim. Only with an awesome show of unity, vigilance and a shared resolve against their grotesque campaign of hatred, will we defeat them.