IF, as suspected, the death of Anwar al-Awlaki was the result of a US drone missile strike, it tells us much about current US counterterrorism strategy regarding al Qaeda.

To begin with, let’s take the man himself before looking at the method of his assassination. While Awlaki was operationally active and linked to at least three al Qaeda plots – including the failed 2009 Christmas attempt to blow up an airliner over Detroit, the 2009 Fort Hood mass shooting, and the 2010 cargo flight explosives plot – his prime role was above all as a propagandist and global messenger.

Educated, articulate, inspirational and above all internet savvy, the real value of this native English-speaking American-Yemeni was his ability to deliver al Qaeda’s message in a way that speeded up the radicalisation of the group’s supporters in both the Islamic world and the West.

Aspiring militants from the disaffected Muslim diaspora in the suburbs of western towns and cities to the volatile backstreets of Pakistan’s North-West Frontier tuned in and listened to his speeches, sermons and lectures that often ran on al Qaeda’s online portal – Inspire. In many of these productions “martyrdom” was celebrated while bombmaking and other how-to guides were provided for would-be terrorists.

This online activity is crucial to al Qaeda’s efforts to shift its operations to self-starting cells, known in intelligence parlance as “clean skins” for their ability to avoid detection by the security services. For years al Qaeda has been deprived of a single physical base or sanctuary. Its response has been to morph into a fluid global franchise whose supporters and sympathisers’ main source of communication is the internet. This was where Awlaki was worth his weight in gold.

In killing Awlaki the US has made clear the urgency with which it sees the threat of al Qaeda’s internet-based network of jihadi followers. His death means the CIA and other security services tasked with battling al Qaeda have struck a deadly blow at the heart of the group’s online armoury. In itself this US counter-terrorism response says much, too, about the possible future evolution of al Qaeda.

Recognising the damage caused to its physical and operational presence in places such as Afghanistan, Pakistan and Yemen, al Qaeda was determined to maintain its online “cult status” that helps maintain the momentum of the terror group’s universal jihadist aims.

Awlaki’s killing has revealed the two-pronged campaign the CIA has adopted in its efforts to dismantle al Qaeda as an effective terrorist force: Hit hard at both its physical and operational activities on the ground while simultaneously puncturing its online portal presence.

At the sharp end of these activities is an army of intelligence monitoring specialists, while the ultimate weapon at their disposal is the predator drone. From the Haqqani Network in the mountains of the Afghan-Pak border to al Qaeda in the Arabian Peninsula (AQAP) and al-Shabaab in the deserts of Somalia, these US drones and their powerful missile payloads have steadily eroded the leadership of the various militias comprising the al Qaeda franchise.

On Thursday it was Awlaki’s turn, yesterday in Pakistan’s South Waziristan tribal region it was three more suspected Islamic militants who were blown to pieces by US drone missiles.

Awlaki may not have been AQAP’s leader – that is Nasser al-Wuhayshi – but he will prove difficult to replace.

Last year Sir John Sawers, the chief of Britain’s Secret Intelligence Service (MI6), singled him out as a major threat following one of Awlaki’s global online speeches. For the moment, al Qaeda’s most accessible and gifted English-language propagandist has gone. The challenge now for Western counterterrorism agencies is to make sure that an equally effective voice doesn’t replace him.