The bomb attacks in Uganda on Sunday night point to yet another front opening up in the battle with terrorism. No group has claimed responsibility but all the signs point to a Somali connection, and specifically to al Shabaab, the al Qaeda affiliate now battling the weak Somali government.

Uganda provides the bulk of the African Union peace-keeping force in Mogadishu, a force known as AMISOM (African Union Mission in Somalia) whose main role is to keep the Somali government from being swept away by Shabaab and its allies.

Shabaab videos describe the peacekeepers as infidels and record ambushes and attacks on their vehicles. There was a devastating attack on the AMISOM headquarters last year – carried out by a Somali-American – that claimed 21 lives. And recently, the militants’ rhetoric against both Uganda and Burundi (which also provides troops for AMISOM) has become even more heated.

Earlier this month, Sheikh Muktar Abdelrahman Abu Zubeyr, Shabaab's “spiritual leader,” released an audiotape that was broadcast on Somali radio stations in which warned that the peoples of Uganda and Burundi would face revenge for their troops' role in Somalia. "You should know that the massacres against the children, women and the elderly of Mogadishu will be revenged against you. Keep in mind that the aggressions being committed by your leaders and soldiers is awaiting you," he said.

"We have to continue an all-out Jihad campaign against the enemy…. That is the only way to end the massacres being carried out by the infidels in our country," the Sheikh said.

Shabaab’s capabilities have developed as more foreign fighters have joined it – many of them bringing experience in bomb-making with them and following Osama bin Laden’s personal appeal for fighters to join jihad in Somalia in March 2009.

The President of Somalia’s Transitional Government – Sheikh Sharif Ahmed – said Friday that the growing number of foreign militants posed a growing threat to regional security. "Somalia is at risk from the growing number of foreign militants (here),” he told Reuters. “Things have gone beyond a level we can tolerate so there is an urgent need for international or regional help.”

The organization’s second-in-command, Mukhtar Robow Abu Masour is an Afghanistan veteran, and Somalia's first suicide bombs are often linked to him. There were several suicide bomb attacks attributed to Shabaab in Mogadishu in 2009.

But until now, Shabaab has not taken its war beyond Somalia, with the possible exception of sporadic incidents in northern Kenya. To Alex Vines, who runs the Africa program at the London think-tank Chatham House, the Uganda attacks would be a significant departure. ”If the radical Islamist group Al Shabaab is involved, this is the first time out of Somalia this has happened with this particular group, and it shows that this has the capability of targeting soft targets outside Somalia” he told CNN.

Intelligence analysts believe that Shabaab may also be benefiting – indirectly – from the piracy that plagues the Horn of Africa. While there is no evidence that Shabaab is involved in piracy, it  may have benefited from levying “taxes” on the multi-million dollar industry. That gives it the funds to expand operations and recruit fighters for cash – in a country where there is no work and poverty is endemic. Local reports say some fighters, in cities like Kismayu near the Kenyan border, are being paid the equivalent of $400 a month to join Shabaab.

To CNN National Security contributor Fran Townsend, Shabaab’s growing capabilities are a cause for concern in the United States. “Over the last year we've heard again and again concerns in the Somali-American community of Al Shabaab recruiting, and then bringing over to Somalia, American-Somalis to train them to fight there. And this has been a real priority for the FBI working with the Somali-American community to try and prevent that from happening, prevent these kids from being pulled into this conflict in Somalia.”

About twenty young Somali-Americans disappeared from Minneapolis in 2007-08; a handful are thought to have left other US cities – including Seattle – to wage jihad in Somalia.

“Once they're trained and they fight, [what] you don't want to see, is them to take that war-like experience and bring it back here to the homeland,” Townsend said.

Uganda’s commitment to AMISOM has shown no sign of weakening despite the casualties its troops (and now civilians) have suffered. But even as it pledges to strengthen AMISOM, the  African Union is tiring of its mission to Mogadishu. Last week it asked the United Nations to replace AMISOM with a UN force of 20,000 troops. That seems unlikely in the extreme: Western governments are already over-stretched in their military deployments overseas (and their public finances) and are still haunted by the deadly quagmire that Somalia became in 1993.

Against that, analysts say the absence of an international presence in the Somali capital would make al Shabaab’s position in southern and central Somalia almost irresistible.