The U.S. military began an operation on Monday against the Somali militant group al-Shabaab, which has links to al Qaeda.

The American force is working with Somali troops and together they are going after top al-Shabaab operatives, senior defense officials told The New York Times. Those officials asked not to be identified.

Rear. Adm. John Kirby, the Pentagon press secretary, said that U.S. officials are still "assessing the results of the operation, and will provide additional information as and when appropriate." Kirby wouldn't reveal any more information about the operation.

A senior Somali official, who asked to be kept anonymous, told The Associated Press that a U.S. drone targeted al-Shabaab leader Ahmed Abdi Godane after a meeting with the group's top leaders, Fox News reported. The official said that intelligence indicated Godane "might have been killed along with other militants."

The U.S. has been supporting an African force of more than 20,000 that has expelled al-Shabaab from previous strongholds in Mogadishu, Somalia's capital, and other urban areas in the region. That force is still fighting the militants in their fortifications across Somalia.

Prior to Monday's military action, the U.S. had about 100 Special Operations forces in different parts of the country, some fighting and some in advisory roles. Nearly all the Special Ops are Navy SEALS.

This is not the first U.S. strike on al-Shabaab in recent times. Last October, Navy Seals raided the town of Baraawe, a known Shabaab redoubt. They were targeting a militant known as Ikrimah, a Kenyan of Somali descent who is a top planner of terrorist attacks outside Somalia.

The SEALS weren't able to apprehend Ikrimah in that raid, which was conducted less than two weeks after al-Shabaab militants stormed a shopping mall in Nairobi, Kenya and killed more than 60 people.

Ikrimah hasn't been tied directly to that attack, but it raised concerns that al-Shabaab could stage a similar assault on Western targets.