US, allied forces attacked in Somalia: Pentagon

United States and allied forces came under attack in Somalia, triggering an airstrike which killed 18 al-Shabaab militants, the US military said on Saturday.

The incident occurred on Friday 50 kilometres (30 miles) northwest of Kismayo in the south of the Horn of Africa country where Somali commandos work side-by-side with the American forces that train them.

Air assaults and missile strikes have increased in recent months.

"The US airstrike was conducted against militants after US and partner forces came under attack," US Africa Command said in a statement.

US forces also partner with the United Nations-backed African Union Mission in Somalia, which aims to counter the threat from al-Shabaab jihadists.

The airstrike was conducted "in self-defence," killing 18 militants, Africa Command said.

Two other militants "were killed by Somali forces with small arms fire during the engagement," it added. 

In August the US Africa Command said four al-Shabaab militants were killed in the 19th US airstrike against the Somalia-based militants this year, the deadliest Islamic extremist group in sub-Saharan Africa.

The group was blamed for the country's worst ever terror attack, when a truck bombing left more than 500 dead in October last year.

The US also has carried out a number of drone strikes against a small presence of fighters linked to the Islamic State organisation in northern Somalia.

In June an American commando was killed during an attack in southern Somalia that also wounded four US military members and a Somali soldier, officials said at the time.

The attack occurred in Jubaland, where a large force comprising about 800 Somali, Kenyan and US troops were working to clear a large area of al-Qaeda-aligned al-Shabaab fighters.

The multinational force "came under mortar and small-arms fire at approximately 2:45 pm Mogadishu time, killing one US service member and injuring four US service members and one partner force member," the US military's Africa Command said in a statement.

More than 500 American forces are partnering with African Union Mission to Somalia (AMISOM) and Somali national security forces in counterterrorism operations, and have conducted frequent raids and drone strikes on Al-Shabaab training camps throughout Somalia.

Last year, a Navy SEAL was killed in a nighttime attack in Somalia, marking the first US military combat death there since the infamous "Black Hawk Down" events of 1993, when 18 American servicemen died in the Battle of Mogadishu.

Since 2007, Al-Shabaab has been fighting to overthrow the internationally backed government in Somalia.

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