The Pentagon has quietly expanded its military operations in Somalia against Al-Shabaab militants in recent weeks.

U.S. drone strikes are now part of a larger U.S. military strategy to provide direct military support to African peacekeepers -- mainly Kenyans -- under attack from Al-Shabaab, two U.S. defense officials told CNN.

Drones, armed with Hellfire missiles, have been flying from a U.S. military site in Djibouti on the strike missions. Other drones conducting intelligence-gathering, surveillance and reconnaissance have been operating out of Ethiopia, according to one of the officials.

The missions are specifically targeting militants in the field who are directly attacking or threatening African Union Mission in Somalia peacekeepers. AMISOM is staffed by troops from nearly a dozen countries, but the bulk come from Kenya and Ethiopia on a regular basis.

Until now, most U.S. military actions in Somalia have focused on airstrikes or raids by special operations forces aimed at capturing or killing specific individuals linked to al Qaeda and other terrorist groups in the region. But in June, Al-Shabaab militants attacked and overran a peacekeeper base in southern Somalia. A spokesperson for the terror group claimed at the time that the group killed 50 soldiers.

It was after that incident that the U.S. military mission to provide overhead protection began to take shape, the officials said. The U.S. assessment is that Al-Shabaab sees a potentially successful strategy in being able to attack and overrun specific targets. The U.S. strikes are aimed at preventing those types of attacks.

In the last 10 days, the U.S. has conducted at least seven drone strikes, and more are expected. On July 14, the U.S. conducted a strike against Al-Shabaab militants to prevent what officials said was an imminent attack on Kenyan peacekeepers. Immediately after that drone strike, African forces on the ground conducted a barrage of artillery strikes leading to more than 50 militants being killed.

U.S. intelligence analysts are also trying to confirm that one of the recent strikes killed two terrorists, Mohamed Kuno and Ismail Jabhad, said to be planners behind the April 2 attack on Kenya's Garissa University that left nearly 150 dead, mostly students. Small numbers of U.S. special forces continue to operate inside Somalia, based mainly at the airport in Mogadishu to help with intelligence-sharing and the training of AMISOM forces.