The US military has secretly maintained forces in Somalia since 2007, despite earlier public statements claiming it had no presence in the country until last October, defense officials said Thursday.

The United States has deployed up to 120 troops in the African nation and hopes to bolster its security ties to Somalia's government as it battles Al-Qaeda-linked Shebab militants, a defense official, who spoke on condition of anonymity, told AFP.

The US troops operating in Somalia have been mainly Green Beret special forces, who specialize in training and advising local armies, the official said.

Reuters news agency first reported the US troop presence.

In October last year, the Pentagon had portrayed the arrival of a handful of military advisers in Somalia as the first deployment of American forces to the country since 1993.

The Pentagon had chosen not to publicly reveal the military's footprint in Somalia out of concern for the safety of troops deployed and out of respect for the "sensitivities" of the Somali government, the defense official said.

But the head of Africa Command, General David Rodriguez, who took over his post last April, favors a less secretive stance particularly as Washington's defense relationship with Somalia progresses, the official said.

"He's wanted to be more open," said the official. "This reflects that approach."

Officials acknowledged that deploying troops to Somalia has long been a sensitive question since a disastrous intervention in 1993, when two US helicopters were shot down and 18 troops were killed in an operation depicted in the movie "Black Hawk Down."

The revelation of the years-long US troop presence comes as President Barack Obama prepares to name the first American ambassador to Somalia since civil war erupted more than 20 years ago.

The United States recognized Somalia's new government in January 2013.

Although Shebab militants have been rolled back out of the capital Mogadishu, large swathes of rural areas are still controlled by the Al-Qaeda-linked extremists.