Expelled from a string of strategic towns, cut off from revenue sources and struggling for its survival, Somalia’s militant group Al-Shabab is steeling for an anticipated assault on its last bastion by Western-backed African forces.

But while the capture of the southern port and militant stronghold of Kismayu in coming weeks could weaken the Al-Qaeda-linked rebels, it is unlikely to deliver the knockout blow hoped for by Mogadishu and its allies.

Kenyan forces operating in Somalia seized the southern rebel stronghold of Afmadow in late May. This opened the way for what Kenyan Prime Minister Raila Odinga said would be a “final onslaught” on Kismayu, Somalia’s second biggest city which is a hub for Al-Shabab and a main base for its foreign fighters.

Kismayu would be taken by August, Odinga said this month.

But some regional diplomats feel this target is over ambitious. There are fears that a wounded Al-Shabab will simply redeploy from Kismayu and hit back with guerrilla raids and urban bombings, disrupting efforts to end two decades of violence in the Horn of Africa state.

“The fall of Kismayu might hurt the rebel economy, but they will launch more attacks,” said Hassan Farah, a shopkeeper in the coastal city. He said the dense forest surrounding the port would be an easy hiding ground for the rebels.

“Al-Shabab will not go far, even if they lose Kismayu.”

The diplomats argue that African Union peace keepers deployed against Al-Shabab need to consolidate their numbers in other recently won urban areas, before the assault on Kismayu.

There are also questions about whether the rebels, wary of possible heavy casualties and an expensive battle, will dig in and defend the densely-populated port that has served as a financial lifeline, or melt into the jungle hinterlands.

“Kismayu has a strong administration under Al-Shabab. The markets are busy and there is security,” said Farah. “I know of many residents who are ready to fight alongside Al-Shabab.”

Natznet Tesfay, a Somalia expert from Exclusive Analysis, said Al-Shabab would likely pull back and turn to guerrilla-style hit-and-run sabotage attacks, as they did in Mogadishu after they were expelled by African troops.

“We are more likely to see a lull in the intensity (of) Al-Shabab activity and possibly a rebranding rather than the group’s collapse,” Tesfay said.

That, Tesfay said, could mean the Islamist movement splitting into splinter groups, between those motivated by a nationalist agenda to establish Shariah in the country, and those motivated by more global jihadi sentiments.

An Al-Shabab suicide bomber on Saturday attacked a government base outside the Somali capital in Afgoye, a town captured at the end of May by Somali government and African Union troops. This underscored the security challenge facing the government and its allies despite their recent successes.

The market town was a cash cow for Al-Shabab which extorted taxes on goods destined for Mogadishu, compounding the financial blow the insurgents suffered last August when they were driven from Mogadishu’s Bakara market, the capital’s economic heart.

In a sign of the mounting pressure on the group, a steady trickle of defections points to low morale within rebel ranks. Defectors tell of Al-Shabab footsoldiers demoralized by battle fatigue, meagre salaries and a lack of sophisticated weaponry.

Mogadishu’s Western allies are keen to capitalize on the group’s troubles. Washington this month offered multimillion dollar bounties for information leading to the location of seven key militant commanders.

But talk of a “tipping point” is premature, analysts say.

“While there are clearly splits within Al-Shabab, divisions which will be exacerbated by the loss of two of the most significant towns still under its control, Al-Shabab has always shown a remarkable resilience,” said J. Peter Pham of US think-tank the Atlantic Council.

“In fact, there is already evidence that the group has laid the foundations for its eventual resurgence after the current setbacks.”

Intelligence picked up by security agencies, research by the United Nations and accounts by Muslim Kenyans suggests Al-Shabab is mentoring a new and increasingly multiethnic generation of militants.

The concern is that an increasingly cornered Al-Shabab may attack more widely in the region, a capability demonstrated by a double bombing in Uganda in 2010 that killed 79 people.

Under pressure in south and central Somalia, diplomats say Al-Shabab is moving combatants to the semi-autonomous Puntland territory that is separated by only a narrow neck of water from Yemen, a hotspot in the US-led war against militant Islam.

“Obviously it’s of concern not just because it could further undermine stability in ... a more secure and stable area, but also because of a potential link up to AQAP (Al-Qaeda in the Arabian Peninsula),” said a senior diplomatic source who follows Somalia.