The move reverses an order from US President Joe Biden's predecessor Donald Trump, who in 2020 pulled nearly all US forces from the East African nation.
President Joe Biden has ordered the reestablishment of a US troop presence in Somalia to help local authorities combat the Al Shabab militant group.
Biden "approved a request from the Defense Department to reposition US forces in East Africa in order to reestablish a small persistent US military presence in Somalia," a senior American official told reporters on Monday.
Fewer than 500 troops will be involved, the official said, adding that it will "take a little bit of time to reach that" level in Somalia.
That is slightly smaller than the original footprint of 750 US soldiers who spent years in the country conducting operations against Al Shabab, but were then removed under Trump and rebased in neighbouring countries Kenya and Djibouti.
In December 2020, just before he left office, Trump directed the withdrawal from Somalia "against the advice of senior US military leadership," the official said.
"Since then Al Shabab... has unfortunately only grown stronger," the official added.
Support from Mogadishu
The official suggested that Biden's decision had more to do with the security of US forces than with the election on Sunday of a new Somali president, Hassan Sheikh Mohamud, after more than a year of political instability and a drought crisis.
Somalian leaders over recent years have been constant in their support for cooperation with the US military in battling Islamic extremists, the official said, adding that Washington remains confident the new administration will continue to do so.
Congratulating the newly elected president, US Secretary of State Antony Blinken urged him to develop "security forces to prevent and counter-terrorism and assume full security responsibility from the African Union Transition Mission in Somalia."
Pentagon Spokesman John Kirby said Monday that Defense Secretary Lloyd Austin viewed the current form of operations as "inefficient and increasingly unsustainable."
"The purpose here is to enable a more effective fight against Al Shabab by local forces... Al Shabab has increased in their strength and poses a threat," he said.
Kirby also insisted that the US forces will act as a supportive element and that Somali forces will continue to be responsible for directly battling extremists.
US troops "will continue to be used in training, advising and equipping partner forces to give them the tools that they need to disrupt, degrade and monitor Al Shabab," the Pentagon spokesman said.
"Our forces are not now, nor will they be, directly engaged in combat operations," he said.