The Ethiopian decision to invade Somalia in December 2006 altered the balance of power in the Horn of Africa.
By Martin Plaut
BBC Africa analyst
The Ethiopian army is now fighting on several fronts
On 28 December 2006, they helped government forces capture Islamists from the capital, Mogadishu, which they had controlled for six months.
Ethiopian forces, which had been facing Eritrea along their 1,000km border, but were otherwise confronting few security threats, are now engaged on three fronts.
The forces in Somalia are now bogged down and cannot withdraw, as Prime Minister Meles Zenawi recently acknowledged.
In addition to the conflict in Somalia they now also confront a growing rebellion in the Somali region of Ethiopia from the Ogaden National Liberation Front.
Knox Chitiyo, head of the Africa programme at the Royal United Services Institute in London, believes the Ethiopian military position is increasingly difficult.
"The government now has daggers pointing at it from all directions," he says.
"It is facing a multi-front war with no prospect of a military victory."
The invasion has:
- Left Ethiopia bogged down in Somalia
Forced around 600,000 Somalis to flee their homes, in what the UN has described as one of the worst humanitarian situations in Africa
- Brought the United States into the conflict, allied to Ethiopia
- Left Eritrea even more isolated from the international community and threatened with being declared a terrorist state by Washington.
The US says it opposed the Ethiopian invasion, although it certainly supplied assistance to the Ethiopian military once the invasion had happened, and used its AC-130 gunships to try to kill senior Islamists on at least one occasion in January 2007.
The US Assistant Secretary of State Jendayi Frazer said: "We urged the Ethiopian military not to go into Somalia."
Many Somalis are opposed to the Ethiopian presence
This is acknowledged by Ethiopian officials, who say the then head of US Central Command, General John Abizaid told them the invasion would be a mistake, and warned that Somalia would become "Ethiopia's Iraq."
Others analysts are not so apocalyptic. Ethiopia argued it had no alternative but to confront the Union of Islamic Courts (UIC) after it took power in Mogadishu in mid-2006, because of the Islamists' alleged links with al-Qaeda.
The declaration of a jihad against Addis Ababa by UIC leader Sheik Hassan Dahir Aweys was seen as the last straw.
But even if the UIC was routed, it has now re-formed and has banded together with other forces in the Eritrean-based Alliance for the Liberation of Somalia.
Sally Healy of the Royal Institute of International Affairs argues that even if Ethiopia has made some security gains, the suffering of ordinary Somalis has been disproportionately high.
"The cost for the people of Mogadishu has been unacceptable," she says.
This reflects the view of the United Nations, which now considers Somalia the worst humanitarian crisis in Africa.
Peter Smerdon of the World Food Programme says it will have to try to feed at least 1.2 million Somalis during 2008.
The conflict is taking a heavy toll on Somali civilians
"More than 600,000 people were forced from their homes in Mogadishu in 2007 by fighting and the worst cereals harvest in 13 years in Middle and Lower Shabelle, traditionally the most agriculturally productive regions of the whole country," Mr Smerdon says.
He warns the numbers needing food aid could well rise if there is continued insecurity and any kind of repeat of the floods and bad harvests seen in recent years.
So how might the Somali crisis be resolved?
Hundreds of thousands of people have been displaced this year
Ethiopia has said it would consider withdrawing its troops if an international peacekeeping force were put in place, but UN Secretary General Ban Ki-moon has said the situation in the country makes such a deployment "neither realistic nor viable".
The UN believes a new initiative is required, bringing together Somalia's Transitional Federal Government and the opposition.
This proposal was put forward by the UN's senior Somali official, Ahmedou Ould Abdallah, when he addressed the UN Security Council earlier this month.
"These discussions should preferably be held in a location close to Somalia or in one where most observers following the situation in the country are based," he said.
"I am preparing the agenda, identifying a possible list of participants, and the timing for this process."
Ms Healy says this is really the only way forward.
Until an exit strategy can be achieved for Ethiopia, its troops will remain in occupation of the country - providing a cause around which the Islamists can rally.
"The Somali people must create a situation that would allow the Ethiopians to leave," she says.
But 16 years after the country last had a functioning national government, there seems little prospect of President Abdullahi Yusuf asserting control of the whole country in 2008.