Al-Shabaab long has been a target of Washington as well: It was designated a foreign terrorist organization in 2008. The group is seeking to turn Somalia into a fundamentalist Islamic state, though it has carried out attacks in other African countries as well.
The attack on Nairobi's Westgate Mall on September 21 thrust Al-Shabaab into the spotlight once again. Washington vowed to support Kenya's government after the bloody raid, which killed at least 67 people.
The Al-Shabaab raid took place before dawn Saturday (late Friday night ET) in the southern Somalian port city of Barawe.
The Pentagon would only say the operation was against a "known Al-Shabaab terrorist." But town residents told CNN the "foreign forces" came via speed boat and stormed a house believed to be a hideout for several top militant commanders, including the group's top leader Ahmed abdi Godane, also known as Moktar Ali Zubeyr.
A senior U.S. official said the Navy SEALs inflicted some Al-Shabaab casualties, and came under fire.
They made the "prudent decision" to withdraw, and couldn't confirm whether they killed their target, the official said.
Abdiaziz Abu Musab, an Al-Shabaab spokesman, said at least one Al-Shabaab fighter was killed in the gunfight. But no U.S. personnel were injured or killed, a U.S. official said.
In recent months, Al-Shabaab's haven in south-central Somalia has been been increasingly squeezed as Kenyan forces fight the group from the south and African Union forces come down from Mogadishu.
At the same time, Al-Shabaab has become even more closely aligned with al Qaeda. The two groups effectively merged last year, said CNN National Security Analyst Peter Bergen.
"This is a group that has adopted al Qaeda's ideology wholesale," Bergen said. "The reason they attacked the mall was not only because it was Kenyan, but also because it attracted a fair number of Western businessmen and others living in Nairobi."