In this photo taken Feb. 24, 2018 and released by the U.S. Air Force, Tech. Sgt. Starr Day, assistant inspector general…
FILE - In this photo taken Feb. 24, 2018 and released by the U.S. Air Force, Tech. Sgt. Starr Day talks with service members during a battlefield circulation site visit at Camp Simba, Manda Bay, Kenya.

The United States has sent reinforcements to a military base in Kenya following Sunday's deadly attack on the base by militant group al-Shabab.

An image distributed by al-Shabab after the attack on a military base in Kenya shows Somalia's al-Shabab militant group's flag, said to be at the Manda Bay Airfield in Manda, Lamu, Kenya, Jan. 5, 2020.

The military's Africa Command said in a statement Monday that its East Africa Response Force has arrived at the Manda Bay airfield to augment security. 

AFRICOM also said it sees no indication that al-Shabab's attack was linked to Iran.

Three U.S. Department of Defense personnel were killed Sunday when al-Shabab fighters assaulted the Manda Bay airfield, which is used by Kenyan and U.S. counterterrorism forces.

A Chicago woman told local media that her son, Henry Mayfield Jr., was one of the three killed.  The U.S. military has not yet identified the victims.

The Kenya Defense Forces said in a statement that five attackers were killed.

Manda Bay is used by U.S. forces to train African partner forces, respond to crises and protect U.S. interests in the region.  AFRICOM said that six civilian aircraft operated by contractors were damaged in the attack.

The attack came days after al-Shabab fighters killed three people on a passenger bus in Lamu County. The Somalia-based militant group was also responsible for a massive explosion in Mogadishu that killed more than 80 people.