Andrew Hammond is an Associate at LSE IDEAS at the London School of Economics, and former UK Government Special Adviser.
British Prime Minister David Cameron has condemned as "pure evil" the release on Saturday of a video showing the murder of British aid worker David Haines potentially by a UK member of the self-described Islamic State terrorist group. The grisly recording, which included a threat to kill a second British hostage, follows the earlier murders by IS of U.S. citizens James Foley and Steven Sotloff.
The incident comes at the same time as around 40 states, including 10 from the Gulf, have signed up to U.S. President Barack Obama's strategy to tackle the Islamic State. While London supports the broad principles of this, its position is not yet clear cut on joining any intensified U.S. airstrikes, partially because of the UK domestic political sensitivities of this following the controversies of the Iraq intervention from 2003 onward.
Last year, Mr. Cameron lost a vote in the UK House of Commons that would have enabled London to launch military strikes in Syria against the regime of President Bashar al-Assad following an alleged chemical weapons attack against citizens in the country. While the Prime Minister asserted Sunday that he ultimately "will take whatever steps are necessary" with regard to IS, Foreign Minister Philip Hammond has been more cautious, appearing to rule out air strikes specifically in Syria against ISIS.
Aside from the issue of degrading the Islamic State's territorial foothold in the Middle East, the tragic killing of Mr. Haines follows concern expressed by Mr. Cameron, Mr. Obama and other world leaders about the threat posed from some foreign jihadists returning to their home countries from Iraq and Syria. Mr. Cameron reiterated this message on Sunday saying The IS may be planning attacks internationally.
The numbers of foreign jihadists who have already returned from the Middle East to their home countries is not certain. However, Richard Barrett, the former head of counter-terrorism at MI6, warned earlier this year that "up to 300" foreign fighters from Syria may now be back in the United Kingdom alone.
It is unclear how many of these individuals have ties to the Islamic State that was created in April 2013 from one of al-Qaeda's affiliate organizations in Iraq. While the IS is therefore technically an offshoot or splinter group of al-Qaeda, both sides have disavowed each other with IS accusing al-Qaeda earlier this year of having "deviated from the correct path", and "divided the mujahedeen in every place".
While it is uncertain how many foreign fighters are in Iraq, the International Centre for the Study of Radicalisation at Kings College London estimates that as many as 11,000 foreign fighters overall may have fought in Syria, from more than 70 countries. As Mr. Obama, Mr. Cameron and others have asserted, a central concern is that many of these individuals, who include potentially as many as 2,000 from Western Europe, plus others from North America, Australia, Southeast Asia, and Africa, will return from Syria and Iraq battle-hardened with significantly greater terrorist capability and resolve. And given that the relatively large number of these jihadists makes them collectively difficult to track with precision, home-grown attacks are possible.
The increased prominence of the Islamic State comes at the same time that al-Qaeda, from which it split, has faced declining fortunes. Some three and a half years from Osama bin Laden's assassination, al-Qaeda's central organisation has been significantly degraded, as the United States and its allies now intend with IS.
While bin Laden's successor, Ayman al-Zawahri, has sought to seize upon home-grown terrorism for propaganda purposes, this cannot disguise central al-Qaeda organization's declining fortunes. Mr. Zawahri lacks Osama bin Laden's personal authority within the network, and the core has also been weakened by the assassination of numerous other senior terrorist leaders.
A fundamental challenge for Mr. Zawahri is that while the central al-Qaeda leadership appears to still remain located largely in Pakistani tribal areas and borderlands, the wider network has becoming increasingly decentralized and dispersed and thus less able to control. This is exemplified by al-Qaeda's tensions with the Islamic State.
The origin of the dispute partially lies in an edict from Mr. Zawahri to IS to confine its activities to Iraq after it was accused of abuses of civilians and rival rebels in Syria. Mr. Zawahri instead had recognised the Nusra Front as the official al-Qaeda affiliate in Syria and called for jihadist unity behind it in that country.
Accompanying this dispersion and decentralization has been shifting focus of al-Qaeda groups and franchises whose attention is generally more on 'local' national or regional issues, rather than the broader international designs of Osama bin Laden. In part, this also reflects the greater difficulty of attacking key international targets many of whose defences have become significantly hardened since 9/11.
There has also been evolution in the geographical focal points of al-Qaeda activity with terrorist nodes of growing importance, for instance, in key African and Middle Eastern countries, such as Yemen, where political upheaval since bin-Laden's death has allowed terrorists and other insurgents to secure greater foothold. And reflecting this changed risk pattern, U.S. forces are redeploying as a result.
Taken overall, ISIS now looks likely to face degradation by a broad coalition of countries. While this will undercut its territorial foothold in the Middle East, danger from home grown terrorism may be growing from some battle-hardened, radicalized individuals returning with greater terrorist resolve and capabilities.