Why Isil and al-Qa'ida are happy to associate with the spilling of blood in Europe
According to some intelligence reports, there could be as many as 20 sleeper cells of between 120 and 180 people ready to strike in France, Germany, Belgium and the Netherlands.
CNN has reported that European Union and Middle East intelligence agencies had identified an "imminent threat" to Belgium, and possibly also to the Netherlands.
European security services in recent weeks have received indications that the extremist group Isil may have started directing European adherents in Syria and Iraq to launch attacks in their home countries, a senior European counterterrorism official told CNN terrorism analyst Paul Cruickshank.
In the dark world of Islamist terrorism, there is rarely any shortage of people seeking to claim credit for carrying out some appalling atrocity. We don't yet know what affiliation will be claimed in the ''jihadist-related" shoot-out in Belgium on Thursday. But we do know that, so far, two Islamist groups have sought to associate themselves with the two attacks last week in Paris in which 17 people lost their lives.
Al-Qa'ida in the Arabian Peninsula (AQAP), the jihadist group formed from al-Qa'ida's Yemeni and Saudi branches and based in the lawless southern mountain region of Yemen, has issued a statement claiming responsibility for the attack on 'Charlie Hebdo'.
American counter-terrorism officials say they have information suggesting that Chérif Kouachi, inset, the younger of the two brothers who carried out the magazine murders, travelled to Yemen back in 2011, where he received training and $20,000 to organise the attacks.
Meanwhile, Islamic State (Isil) militants based in Syria and Iraq have indicated that they were behind the attack on the kosher hypermarket in Paris which was carried out almost simultaneously by Amedy Coulibaly. This may well be the case for, while the Kouachi brothers told onlookers they were AQAP members, Coulibaly announced that his affiliation lay with Isil.
The narrow distinction between the groups may not be of much concern to those struggling to come to terms with the worst French terrorist attack for 50 years. Yet the fact that AQAP and Isil, supposedly sworn enemies, are now boasting about their combined involvement does illustrate the increasing complexity of Islamist terror networks, and the deepening challenges Western intelligence and security services face in trying to disrupt them.
Until last week, most counter-terrorism experts were under the impression that the threat posed by the Yemeni-based militants was in decline, particularly after a US drone strike in 2011 killed Anwar al-Awlaki, AQAP's charismatic, American-educated propagandist. The group's demise was said to have been further hastened by the emergence of Isil, which, after its rapid advance through northern Syria and Iraq, replaced al-Qa'ida as the world's most feared terror organisation.
AQAP's eclipse, moreover, seemed to be confirmed by the deep rift which emerged with Isil over its brutal treatment of Muslims in the Syrian and Iraqi conflicts.
Ayman al-Zawahiri, the elderly Egyptian cleric who took over from bin Laden at the head of the original al-Qa'ida franchise, publicly denounced Isil's barbarous tactics last year, only for his remonstrations to be treated with disdain by the new boys on the Islamist block.
But, as the Paris attacks have graphically demonstrated, while AQAP may have faded from public view, it has lost none of its ability to carry out extreme acts of violence.
In recent months, the organisation that trained the "underpants" bomber, as well as attempting to smuggle sophisticated explosive devices within printer ink cartridges, has benefited from the arrival of scores of al-Qa'ida fighters fleeing the assault on their traditional hideouts by the Afghan and Pakistani military.
Sheikh Nasser bin Ali al-Ansi, a former bin Laden protégé who appears in the video claiming responsibility for the Paris attacks, is believed to be only one of several prominent al-Qa'ida figures who have relocated to Yemen.
Indeed, the ability of terror cells to regroup and rebuild in different locations is a particularly worrying feature of the mounting threat that they pose.
There is nothing al-Qa'ida and its affiliates like more than to move into the ungoverned territory created by failed states. Apart from Yemen, Islamist militants have also established themselves in Libya.
The same applies in neighbouring Mali and the rest of the Maghreb region, where the growing number of militants has been most useful for Boko Haram, which is waging a campaign of terror in northern Nigeria.
But if Islamist groups are proving adept at creating independent fiefdoms in failed or failing states, last week's attacks worryingly show that rival Islamist factions, for all their apparent ideological differences, are perfectly willing to work together when it is in their interests to do so.
The lesson from Paris must be that if the West wants to prevent further attacks, then it must do everything in its power to ensure that failed states no longer provide safe havens for Islamist fanatics. (© Daily Telegraph, London)