By David Wright-Neville Monash University, Melbourne

While it is true that some of these arrests, especially that of JI's senior logistics person, Hambali, have damaged the organisation's operational potential, the group's regional spread remains intact.

JI are alleged to have established cells throughout the region

But the arrest of Hambali, and over the past year almost 100 other alleged JI members, is certain to have placed the organisation and its pursuit of these goals under significant operational pressure.

JI's goals

Formed in the mid-1980s by two Indonesian clerics, the JI evolved its terrorist edge in the mid-1990s when one of its founders, the late Abdullah Sungkar, established contact with Osama Bin Laden's al-Qaeda network.

While Abdullah Sungkar oversaw the JI's political and strategic development, several South East Asian intelligence agencies name Abu Bakar Ba'asyir as the group's spiritual leader. He is currently facing treason charges in Indonesia.

The JI's principal goals are the establishment of Islamic governments across the region followed by the formation of a unified South East Asian Islamic state.

This state would stretch from southern Thailand, through the Malay Peninsula (including Singapore), across the Indonesian archipelago and into the southern Philippines.

Claims that JI aspires to include parts of Northern Australia in this Islamic super-state remain unproven. Nor is there any evidence that JI's vision is shared by anything more than a tiny number of South East Asia's 300 million Muslims.

To achieve its goals the JI espouses the waging of a "holy war" to purge the region of un-Islamic influences and ready the ground for Islamic government.

Under pressure

With the arrest of Hambali, JI has now lost its three most senior officials and no one individual appears to have the charismatic or religious authority needed to fill the gap.

Jemaah Islamiah has been blamed for the Bali attack in October 2002

Moreover, there is evidence that ideological and operational divisions have recently opened up within JI. The absence of a strong leadership core could see these divisions widen, a development that would undermine JI's ability to co-ordinate across the region.

There is no reliable information on the exact number of individuals contained within this network; estimates range from several hundred to several thousand.

The actual number probably lies somewhere between these two extremes, with the majority scattered across the sprawling Indonesian archipelago.

Robbed of its senior leadership, the network will struggle to carry out an attack against a high value target, such as a government office or Western diplomatic mission.

However, eager to send a message of resilience and deny their enemies the accolades that flow from such high profile arrests, there is a risk that different parts of the network will intensify their focus on 'softer' targets, such as bars, nightclubs and hotels.

To this end, a number of younger and highly skilled JI cadre, such as Dulmatin, Azahari bin Husin, and Fathur al-Ghozi, who recently escaped from a Philippines jail, remain at large and capable of co-ordinating terrorist attacks, if not assuming a leadership role.

Al-Qaeda links

The fragmentation of JI's cohesion might also complicate links with al-Qaeda. Until recently Hambali appeared to have been the principle conduit through which both organisations communicated, a position he inherited on the death in the late 1990s of Abdullah Sungkar.

While the precise nature of JI's relationship with al-Qaeda is a topic of debate, informal links between the two organisations have grown in recent years.

In fact it was the simultaneous presence at al-Qaeda camps in Afghanistan by militants from across South East Asia that facilitated many of the personal relationships that exist between JI and members of other violent South East Asian Islamist groups.