The Burnhams have been missing since May 2001

The army says that their offensive has steadily reduced the guerrillas as a fighting force, and liberated all but three of their hostages, including two Americans, Gracia and Martin Burnham.

"If we could get the hostages, then I think the Abu Sayyaf is no more," says Colonel Gabriel Ledesma of the First Scout Rangers battalion - one of the key frontline units that have been battling the group.

That confident assessment suggests an ambivalence on the part of the Philippine military at the prospect of working alongside foreign forces - even those of a strong ally like the United States.

Training role

While local commanders may appreciate US technical assistance and expertise, the implication that their men are not up to the job of crushing a home-grown terrorist group seems to rankle.

Some newspaper commentators have described President Gloria Arroyo's decision to solicit Washington's help against the Abu Sayyaf as a blow to the pride of her own military.

The soldiers are training in challenging terrain

Ostensibly, the role of the 660 US soldiers involved in operation Balikatan (literally "shoulder to shoulder") will be limited to training.

But American commanders acknowledge that once the exercises are in full swing, some GIs - probably including special forces troops - will take part in joint patrols deep inside Abu Sayyaf territory on Basilan.

Making the task of the Americans harder is the attitude of the majority Muslim local community. While the number of armed and active Abu Sayyaf guerrillas may be as few as 80 to 100, they count many sympathisers among the local population.

Angry protests

Former congressman, Candu Muarip (himself a one-time rebel fighter with the Moro National Liberation Front) likens the task to hunting for the proverbial needle in a haystack.

"They know the terrain, they know where to hide. They have relatives, even in the towns," says Muarip. "They can scatter themselves, and the government, the military cannot pursue, one by one, all of the Abu Sayyaf."

There have been regular anti-American protests

Another pitfall for the Americans is the presence on Basilan of units belonging to a much larger rebel group, the Moro Islamic Liberation Front (MILF).

The MILF agreed a ceasefire with Manila last year as a prelude to negotiations over the group's demands for a separate Islamic state. The MILF has warned the Americans to keep clear of their positions.

Demonstrations against the US military involvement have occurred regularly in recent weeks in the capital, Manila.

While some Filipinos see the return of American forces as a breach of the constitution, even a return to colonial subjugation, observers in Basilan believe it will only worsen the security problems on the island.

"The solution to the problems of Basilan is not a military one," says Herminio Montebon of the Basilan Muslim-Christian Alliance for Peace. "The problem is poverty, and the government should listen to the cry of the people here. We need livelihood for our people, we don't need war in Basilan."