A year - almost to the day - since they declared a caliphate in Syria and Iraq, the group that calls itself Islamic State has achieved one of its great goals - the mass slaughter of British citizens.
The attack was on Britain, even though it was in Tunisia. The country known as ‘the lighthouse of the Arab world’ was always a likely target for a proxy strike against the UK - a place where the transition towards democracy disgusts extremists and the golden beaches attract tourists.
British holidaymakers appear to have been singled out by the laughing gunman.
And so, suddenly, the perceived threat to the UK from ISIL has become a real one.
Murderers on three continents - whether acting under direction or as ‘lone wolves’ - chose the holy month for their Bloody Friday.
The slaughter at a beach resort was the bloodiest expression of their poisonous ideology.
Though we do not know whether the attacks in Tunisia, Kuwait and France were co-ordinated by ISIL, it would be surprising if the group's recent calls for slaughter during Ramadan didn’t play a significant part in all three.
Predictably, David Cameron today vowed to defeat ISIL - what he couldn’t explain is how.
Britain’s contribution towards the coalition air campaign has been limited; the deployment of ground troops has been ruled out; only a small amount of arms have been provided to the Kurds, who are making some gains, including today in Kobane.
Perhaps at home, the efforts have been more robust.
In 11 days, following the tenth anniversary of the 7/7 attacks, we will be able to say that Islamist terrorism has claimed only one life in Britain in a decade.
The death of soldier Lee Rigby on the streets of Woolwich was tragic and gruesome - but there is no doubt that our security services had expected more.
Compare that toll with France, where the Charlie Hebdo slaughter was one of several attacks by jihadists over the last year.
But terrorism’s impact is not only measured in death tolls but in fear. There is plenty of that. Hours after the Tunisia killings, security in London was being elevated ahead of celebrations for Armed Forces Day.
With the number of British casualties in Tunisia creeping up, it seems increasingly difficult to not see the threat posed by jihadist groups across the world as a specific concern for Britain.