"I can confirm that the US military conducted an operation in Somalia yesterday against the al-Shabaab network.”
"US officials are continuing to assess the results of that operation, and we will provide some additional information as appropriate," White House Press Secretary Josh Earnest told reporters at his daily news conference.
Al-Shabaab was named as a foreign terrorist organisation by the United States more than six years ago.
Earnest said under the leadership of Ahmed Godane Al-Shabaab has conducted several bombings, including suicide attacks in Mogadishu and in northern and central Somalia.
"Many of the targets of those attacks were officials and perceived allies of the federal government of Somalia.”
"Famously, or infamously, in September of 2013, Godane publicly claimed al-Shabaab was responsible for the Westgate Mall attack which killed and injured dozens in Nairobi, Kenya," he said.
The air strike comes days after African Union troops and government forces launched "Operation Indian Ocean", a major offensive aimed at seizing key ports from the Islamist rebels and cutting off one of their key sources of revenue.
Al-Shabaab has also targetted Westerners, including US citizens in East Africa, he said.
In recent months, Al-Shabaab had claimed responsibility for a suicide bombing in Djibouti that killed a Turkish national and wounded several Western soldiers, as well as a car bomb at the Mogadishu Airport that targeted and killed members of a UN convoy.
Al-Shabaab was responsible for the twin suicide bombings in Kampala, Uganda on July 11, 2010, which killed more than 70 people, including one American, the official said.
"So, this is a threat that we have been aware of and countering for quite some time. And the United States stands with our international partners, particularly the African Union mission in Somalia that are working to support the federal government of Somalia build a secure and stable future for the Somali people," Earnest said.
The US has worked closely with its international partners and the government of Somalia to counter the threat from Al-Shabaab, he said.
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