Somali rebels on Monday vowed to avenge a deadly Kenyan air raid as the two countries' prime ministers met over the controversial military assault launched by Nairobi two weeks ago.
While both Kenya and the Somali government are battling the Al Qaeda-linked Al Shabaab insurgents, Nairobi's decision to send troops and warplanes across the border had caused unease in Mogadishu.
A raid on a southern Somali town Sunday killed at least five civilians, including three children.
Kenya insists it hit an Al Shabaab target but witnesses and aid sources said one bomb ploughed into a camp of displaced civilians.
"Kenya has brutally massacred civilians already displaced by hardship ... We will ensure that Kenya mourns more than we did," a regional Al Shabaab official Sheikh Abukar Ali Ada told reporters.
"They cowardly killed around 15 civilians. We will similarly target them and take revenge," Ada said.
Doctors Without Borders said at least five civilians were killed in the air raid, which struck a camp hosting 9,000 internally-displaced Somalis in Jilib.
The military onslaught followed the abduction earlier in October of two Spanish aid workers from the sprawling Dadaab camp which hosts almost half a million refugees, mainly Somalis who have fled conflict and famine.
After meeting in Nairobi, Kenyan Prime Minister Raila Odinga and his counterpart from the Western-backed transitional federal government (TFG) in Mogadishu, Abdiweli Mohamed Ali, said they were fighting a common enemy.
"Al Shabaab constitutes a threat to both Somalia and Kenya and is therefore a common enemy for the entire region and the world. This threat must be fought jointly by the two nations with support from the international community," a joint statement said.
"The Somalia government supports the activities of the Kenyan forces, which are being fully coordinated with the TFG of Somalia and being carried out in the spirit of good neighbourliness and African unity."
Last week, Somali President Sharif Sheikh Ahmed said he was opposed to Kenya's raid launched a fortnight ago, insisting that his government would accept only military training and logistical support.
His TFG exercises little control over the vast war-wracked country beyond central Mogadishu.
There was also some cacophony on the Kenyan side, with Kenyan Deputy Foreign Minister Richard Onyonka saying Nairobi was open for talks with the Al Shabaab, contradicting the government's spokesman's remarks ruling out any negotiations.
Kenya's military chief General Julius Karangi has also said they would not negotiate with the Al Shabaab.
After carefully avoiding being dragged into the Somali chaos, Kenya admitted on October 16 it had sent troops into Somalia, a country whose chaos has defeated all foreign interventions and peace efforts for two decades.
He told reporters Saturday that the forces will pull out "when the Kenyan government and the people of this country feel they are safe enough."
The move was aimed at preventing further attacks on its territory by the Al Shabaab militia, which it blames for a string of kidnappings of foreigners which threaten to cripple Kenya's crucial tourism industry.
However the air and land operation has heightened the security threat inside Kenya, which the Al Shabaab, who deny any involvement in the kidnappings, have vowed to strike in the heart of its dearest interests.
Kenyan security forces say they have stepped up surveillance and last week a 28-year-old Kenyan was jailed for life after confessing to being behind a grenade attack in central Nairobi that killed one and wounded several.
A senior Al Shabaab official on Thursday urged the groups' sympathisers in Kenya, which has a large population of ethnic Somalis, to launch attacks.
The Al Shabaab claimed responsibility for July 2010 bombings in Kampala which the group said were in retaliation for Uganda's leading role in the African Union military mission that has propped up the weak Somali government since 2007.
Observers have also argued that the Kenyan offensive could spur local operatives to carry out lone attacks inside the country.