But any response to the executions must recognise that Islamic State (IS) is not just a loose collective of militants; it is a highly sophisticated group, and as the execution videos have shown, it’s been cautiously and intelligently planning ahead for some time.
IS is clearly tightly organised and effectively run. Its leader, Abu Bakr al-Baghdadi, is a tough and single-minded man who, like bin Laden, sees IS’s chosen fight in absolute, eschatological terms; it has an intense religious underpinning, will stretch decades into the future, and is not just of this life.
Bahgdadi has around him a group of highly intelligent operators, some of them with a decade or more’s combat experience – including in Iraq, where they were pitted against well-armed and well-trained US soldiers and marines.
IS has also shown it’s ready to compromise when it is in its own interests. Witness the close working relationship with Ba’athists in running the city of Mosul after the IS takeover. One could almost say it is single-minded in its willingness to compromise in its pursuit of longer-term, grander aims.
The group has easily outperformed various other Jihadist groups in its use of social media, tailoring its output on any particular issue - such as the recent executions - to target it at a number of specific audiences. These include Western governments, Western public opinion, young Muslims in the West, the wider Muslim world, and in particular disaffected youth across the Middle East.
Most importantly, IS’s leadership will have expected the West to deploy some kind of force once the group came to be seen as a serious threat in the oil-rich Middle East. This is why hostages have been kidnapped and held for months or years. Once US air strikes started, IS was well prepared to use the brutal option of hostage executions in response.
The executions may have been accelerated in response to the intensity of recent US air strikes - well over a hundred to date - but they would nevertheless have been intended at some stage. Put bluntly, IS always knew it would come up against the “far enemy” of the US and its allies. The question was not if but when, even with the cautious Obama in the White House.
What is not entirely clear is the extent to which IS wants the foil of large-scale intervention by the West, including in Syria. It certainly expects it at some stage; that will leave it well-placed to present itself as the vanguard of resistance against yet more Western encroachment on the Muslim world, after Afghanistan, Iraq, Libya, Yemen, Somalia, Mali and even Gaza.
While the great majority of Muslims do not accept this, it strikes a chord with some, especially the disaffected young – providing further potential recruits to the cause.
If the UK joins in the air strikes, or if Obama significantly intensifies them, they will find that IS will have planned accordingly. How they will react to any such engagement is very difficult to say.
But based on the group’s performance so far, we can expect their response to be surprising, and brutal.