This time it is the northern city of Manchester. At time of writing, 22 were dead and more than 50 injured after a suicide attack at an Ariana Grande concert at the Manchester Arena. ISIS has claimed credit for the attack, which was carried out by a 23-year-old called Salman Abedi. There are unconfirmed reports he was a British national.

The bloodbath in Manchester follows on from the vehicular and knife attack in Westminster, London in March, which killed five and injured dozens more. It is also occurred four years to the day since two radicalized British Nigerians hacked a British soldier to death on the streets of London.

Manchester itself is no stranger to Islamist terrorism. Twelve individuals convicted of Islamism-related offences in the UK have lived there. Jamal Harith, a terrorist from Manchester formerly detained at Guantanamo Bay, recently committed a suicide attack in Iraq.

Indeed, one of Al Qaeda’s most significant and heinous plots in Europe over the last decade targeted Manchester. A car bomb was to target a shopping mall in Manchester, with suicide bombers set to detonate their devices as civilians tried to escape the carnage. The cell was arrested in April 2009 and files discovered at Osama bin Laden’s Abbottabad compound in Pakistan tied him directly to the cell.

The choice of venue is also no great surprise. Islamists like to go after such soft targets.

In 2004, police arrested an al-Qaeda-trained cell that had discussed attacking the Ministry of Sound nightclub in London: five men were jailed for life. One of those implicated in the plot was secretly recorded saying, “No one can turn around and say: 'Oh, they were innocent, all those slags dancing around'” (which provides an insight into how these terrorists justify their acts).

Then, in 2007, Tiger Tiger nightclub in central London was targeted by al-Qaeda in Iraq (the precursor group to ISIS) with car bombs – which, fortunately, failed to detonate.

Years later, in 2015, Le Bataclan venue was hit as part of an ISIS cell which launched coordinated attacks across Paris, killing 130. Then, last summer, Omar Mateen murdered 49 people at the Pulse nightclub in Orlando, Fla. He had pledged allegiance to Abu Bakr al-Baghdadi, the emir of ISIS.

Over in Germany, a suicide bomber who had entered the country as a refugee from Syria carried out a suicide bombing near a music festival in Ansbach, injuring 15. He too pledged allegiance to al-Baghdadi.

The UK must now respond to this latest outrage. Practical questions about how this attack took place need to be asked. Where was Abedi able to acquire the expertise to construct this bomb? Had he traveled abroad to receive training? Was he part of a broader network, and if so, how large is it? Are other attacks imminent?

Like Khalid Masood, the terrorist who committed the attack in Westminster, Abedi was on the intelligence radar but considered a lower risk case. The British intelligence services are world class, but no agency can get it right every time – and with both this year’s London and Manchester attacks, two people on the radar have been able to carry out attacks. MI5 will be analyzing what, if anything, went wrong.

Even once this is known, there is no escaping the reality that the threat picture in UK is very troubling and will remain so for the foreseeable future. The intelligence agencies currently assess the overall risk of an attack to be “severe,” meaning another attack is “highly likely.” Part of the reason for this is that approximately 850 Brits have traveled to Syria to fight in the conflict there. Many will have joined ISIS and are returning with training and combat experience. The UK will remain under threat.

The barbarism of this attack -- targeting a concert overwhelmingly attended by teenage girls and children -- is almost unspeakable. Yet this is the nature of the ideological enemy we face: there are no limits to the kind of carnage they wish to unleash.

Until the scourge of Islamist ideology is eradicated, the horrendous images that we have seen over the last 24 hours will appear time and again.