The U.S., which supports Somali forces and their partners, struck in self-defense against a concentration of al-Shabab fighters about 300 miles southwest of Mogadishu, U.S. Africa Command (AFRICOM) said in a statement.
"Al-Shabab has pledged allegiance to al-Qaeda and is dedicated to providing safe haven for terrorist attacks throughout the world," AFRICOM said. "Al-Shabab has publicly committed to planning and conducting attacks against the U.S. and our allies."
Tuesday's strike was different from two offensive strike operations conducted on June 11 and July 2 that were carried out under new authorities granted by President Donald Trump in late March.
Those authorities temporarily designate portions of Somalia south and west of Mogadishu as active areas of hostilities, which means the U.S. may conduct offensive airstrikes there. Until that authority was granted, the U.S. could conduct strikes only in self-defense, like the one carried out Tuesday, in support of Somali troops and their U.S. advisers.
A U.S. official told ABC News that the July 2 drone strike targeted one person.
While the Pentagon has not publicly named that individual, local media identified the target as Ibrahim Haji Daud, a senior al-Shabab commander and the leader of the group's intelligence unit.
The U.S. has about 50 service members in Somalia, advising and assisting members of the Somali military in its fight against al-Shabab.