AP

IS A regional war about to erupt in Somalia? Eyewitness reports on Monday October 9th suggested that “several hundred” Ethiopian soldiers, perhaps three battalions, had entered the small town of Burhakaba, well inside Somali territory. There have long been reports of Ethiopian troops at the town of Baidoa, 65km to the north, where a UN-recognised (but not widely Somali-recognised) transitional government sits. And there have been regular and credible reports of Ethiopian military planes landing on dirt strips up and down the country.

Ethiopia has claimed, not very convincingly, that it has no soldiers inside Somalia. In fact it seems that the soldiers were sent in as a response to an approach by Islamist forces, soldiers under the control of a de facto government in Mogadishu, known as the Islamic courts, to within 20km of Baidoa late last week. There has been no fighting, yet. The Islamists were undermanned in the town and retreated without a shot being fired. But such calm is unlikely to last. Burhakaba is a strategically useful forward base for any attack on Mogadishu. Islamist leaders have vowed to take back the town; some unconfirmed accounts say they already have.

In any event, the Ethiopian involvement may have already triggered a conflict. The Islamists have consolidated their remarkable hold over central and south Somalia by appealing to nationalist as well as religious sentiment. By denouncing Ethiopia at every turn, the Islamists are reaching beyond the country's divisive clan politics. In response to the Ethiopian incursion, the Islamists in Mogadishu have declared a jihad, or holy war, against Ethiopia.

Particularly worrying, that declaration came from a leading moderate in the Mogadishu camp, Sheikh Sharif Ahmed. Mr Ahmed had been involved in negotiations for a power-sharing deal with the transitional government in Baidoa. That now looks very much in doubt. A usually peaceful character, Mr Ahmed was seen dressed in combat fatigues and brandishing an AK-47 as he declared war. He told Somalis to “await orders” and announced the raising of a force to drive Ethiopians and foreign peacekeepers, including a few Ugandans, out of Somalia. He denounced some members of the transitional government as traitors.

Some of this is undoubtedly bluster, designed to keep a fractious coalition happy. Although they confiscated weaponry and armoured jeeps from the Mogadishu warlords routed earlier this year, the Islamists have no conventional army to speak of. Intelligence reports suggest that Eritrea and shady Arab sponsors may have passed the Islamists heavy anti-aircraft guns and bits of other air defence systems made in Russia and Ukraine. Should the fighting escalate, these may deter Ethiopian planes from striking at targets in Mogadishu. In other respects the Islamists are ill-equipped to take on the larger Ethiopian force in conventional warfare. Instead, radicals among the Islamists may respond to the Ethiopian incursions with terrorist strikes.

A bombing campaign inside Ethiopia, where a large Muslim population exists, or even attacks in Kenya, could prove devastating for the region. It could also give weight to Osama bin Laden's call for the Horn of Africa to become the world's third jihadist front, after Iraq and Afghanistan. Of particular interest to the jihadists is luring Ethiopia, an ancient Christian civilisation, into a war against Muslims.

Ethiopia's motivation is mixed. It worries that Eritrea, an old foe, is supporting the Islamists in Somalia. It blames Somali Islamists for a number of bomb attacks in Addis Ababa, the Ethiopian capital, and elsewhere in central Ethiopia. Ethiopia's prime minister, Meles Zenawi, a former rebel leader himself, has promised a hard response to further bombings in an effort to put off any potential new rebel groups inside Ethiopia. That is risky, but his government is worried by the threat from Mogadishu. Mr Zenawi should know about that: he once sheltered in Mogadishu as a rebel fighter seeking to bring down the regime in Addis Ababa.