By Paul Reynolds
World affairs correspondent, BBC News website
One of the targeted suspects has been indicted in the US
By attacking Islamist fighters in Somalia the United States is trying to achieve two objectives.
It wants to intervene decisively on the side of the transitional government now back in Mogadishu and to get at three al-Qaeda suspects linked to bombings of its embassies in Kenya and Tanzania in 1998 and attacks on an Israeli-owned hotel and airliner in Kenya in 2002.
The air strikes were carried out by a huge AC-130 gunship in the south of the country where supporters of the Union of Islamic Courts have retreated under attack from the Ethiopian army and soldiers of the transitional government.
US aircraft have carried out reconnaissance flights over Somalia and it is believed that the US provided Ethiopian forces with intelligence support during the recent offensive.
At the same time, US warships have been patrolling the Somali coast to prevent any escape by sea.
The strategy is to ensure that the Islamist fighters do not regroup and pose a threat to the government.
Only last week a statement believed to be from al-Qaeda's number two Ayman al-Zawahiri urged Muslims to "rise up to aid their Muslim brethren in Somalia".
The Americans and their Somali and Ethiopian allies therefore feared a guerrilla war that might threaten efforts to establish the new government. They are determined to stop the Islamic Courts from resuming power.
The American action was not a random affair but intended to minimise the likelihood of an Islamic insurgency developing
Chatham House analyst
At the same time, there was a more specific American aim behind the attack.
From their special forces base in nearby Djibouti, the US has been watching three al-Qaeda suspects in particular who took refuge in Somalia. It seems that they were among the targets of this operation.
The three are Fazul Abdullah Mohammed, Abu Talha al-Sudani and Saleh Ali Saleh Nabhan.
Fazul Abdullah Mohammed, from the Comoro Islands, was indicted by a US court in New York for conspiracy to bomb the American embassies in Kenya and Tanzania in 1998.
Abu Talha al-Sudani, a Sudanese, was accused by the office of the US Director of National Intelligence recently of leading an al-Qaeda cell in East Africa.
Saleh Ali Saleh Nabhan, a Kenyan, is on an FBI wanted poster in connection with the bombing of an Israeli-owned hotel and an attempted missile attack on an Israeli airliner in Kenya in 2002.
The US sees the break-up of the Union of Islamic Courts as a good opportunity to try to remove what it regards as a serious threat from al-Qaeda in the region.
As well as intervening on the battlefield, the US and other governments are acting to shore up the government of President Abdullahi Yusuf by encouraging the formation of an African Union force to act as peacekeepers.
The Security Council gave its approval for such a force in resolution 1725 in December. That was before the Ethiopian offensive but the authority can now be acted on.
"The work for the transitional government has only just begun," says Sally Healy, Horn of Africa watcher at Chatham House in London.
Al-Qaeda's number two allegedly urged Muslims to fight in Somalia
"It is not clear if they will establish themselves and we might even see a return to the warlords. Ethiopia might have to stay there longer than it really wants because the government is so weak.
"There is a lot of international willingness to support the transitional federal government [TFG] but the issue is when this can become a real government. An AU force is already backed by the UN but it takes time to get one organised. So the TFG needs a deal with local clans and efforts to this end are being led by the Prime Minister Ali Mohamed Ghedi who is from the south, unlike President Yusuf.
"The American action was not a random affair but intended to minimise the likelihood of an Islamic insurgency developing."