After the worst mass shooting in modern US history, theories and accusations abound. This was a hate crime against the LGBT community, not a terrorist incident; the perpetrator was religious/not religious; he was mentally ill/not mentally ill; may or may not have pledged allegiance to ISIS prior to or during the shooting; there was no apparent direct contact with ISIS.

While more will be known as the investigation proceeds, it is fair to say that this appears to be another example of the type of ISIS-inspired terrorist attacks that ISIS spokesman Muhammad al-Adnani has called for, and which are virtually impossible to prevent. It may well be that direct links between ISIS and the shooter will not be found because they may well not exist. Under enormous pressure on the battlefield, ISIS is hardly in a position to provide operational support to attack planning in the West. That is particularly the case in the US.

But this matters little, because rather than practical support, ISIS seeks to provide inspiration. In late May the ISIS spokesman released an audio message in which he said 'Ramadan, the month of conquest and jihad. Get prepared, be make it a month of calamity everywhere for the non-believers...especially for the fighters and supporters of the caliphate in Europe and America'. Mateen's decision to purchase an AR-15 assault rifle and a 9mm pistol during the first week of Ramadan may mean that he followed Adnani's exhortation.

In this modern version of Islamist terrorism, the direct link between ISIS and the jihadi may be no more than the al-Adnani missive. Buy yourself a military-grade semi-automatic weapon, select a soft target, transport yourself there then begin shooting. The whole operation is made all the easier because God loves jihadis, so there is no need to plan an escape. Terrorism has never been more straightforward.

The investigation may reveal a history of viewing or downloading online ISIS or other Islamist material, or of suspicious travel or contact with radicals, or it may not. But the publicity that Adnani's calls for attacks in the West has received may even render a history of viewing material online irrelevant.

This is identity terrorism, where ISIS appeals to people based on their version of Islamic identity that is simple, and guidance that is broad: kill people in your own countries; make something of your life by supporting the aims of one's Islamic brothers fighting oppression in Syria, Iraq, Egypt, and Yemen.

Occasionally, ISIS plans and executes an attack, as was the case with the 2015 Ramadan suicide bomb attack on a Shi'a mosque in Kuwait that killed 26 people. And in the case of the Paris and Brussels attacks, some experienced ISIS personnel were involved. But the signature left behind by more complex planning and attacks can lead to compromised operations, so ISIS-inspired rather than ISIS-planned terrorist attacks have become the norm in the West.

Targeting and operational planning is left up to the individual. With this loose guidance, it is possible for jihadists to combine personal hatreds with direct action. The San Bernardino shooting in December last year targeted Syed Farook's colleagues, while in the Orlando case the target was a gay nightclub more than 150km from where the shooter lived, perhaps reflecting the shooter's alleged homophobia. As far as ISIS is concerned the target matters little, as long as it causes a significant number of casualties and can be claimed by the organisation.

So, rather than deciding whether such attacks are conducted by homophobes, or angry men with invisible lives, or by the mentally ill, we should try to understand the ability of ISIS to motivate small numbers of Muslims to kill their fellow citizens by appealing to a distorted sense of religious identity, and to channel the anger that real or perceived injustices have fomented. And in this regard we are still some way from understanding the triggers that enable some Muslims to equate their religious identity with an obligation to kill innocents from all walks of life and from all faiths and ethnic groups. Until we do, expect more of these types of attacks, even after ISIS suffers a terminal defeat on the battlefield.

Photo courtesy of Flickr user Victoria Pickering