The US military has been involved in Africa for more than two centuries, beginning with the Barbary Wars of 1801-05 and 1815, continuing to the World War II North Africa campaign to the present day.
Below is a timeline compiled by US Africa Command highlighting US military activity in Africa:
Somalia. On June 10, 1993, President Clinton reported that in response to attacks against UN forces in Somalia by a factional leader, the US Quick Reaction Force in the area had participated in military action to quell the violence. On July 1 President Clinton reported further air and ground military operations on June 12 and June 17 aimed at neutralising military capabilities that had impeded UN efforts to deliver humanitarian relief and promote national reconstruction, and additional instances occurred in the following months.
Rwanda. On April 12, 1994, President Clinton reported that combat-equipped US military forces had been deployed to Burundi to conduct possible non-combatant evacuation operations of US citizens and other third-country nationals from Rwanda, where widespread fighting had broken out. By September 30, 1994, all US troops had departed from Rwanda and surrounding nations. In the Defence Appropriations Act for FY1995, Congress barred use of funds for US military participation in or around Rwanda after October 7, 1994, except for any action necessary to protect US citizens.
Somalia. On March 1, 1995, President Clinton reported that on February 27, 1995, 1,800 combat-equipped US armed forces personnel began deployment into Mogadishu, Somalia, to assist in the withdrawal of UN forces assigned there to the United Nations Operation in Somalia (UNOSOM II). This mission was completed on March 3, 1995.
Liberia. On April 11, 1996, President Clinton reported to Congress that on April 9, 1996 due to the "deterioration of the security situation and the resulting threat to American citizens" in Liberia he had ordered US military forces to evacuate from that country "private US citizens and certain third-country nationals who had taken refuge in the US Embassy compound...."
Liberia. On May 20, 1996, President Clinton reported to Congress the continued deployment of US military forces in Liberia to evacuate both American citizens and other foreign personnel, and to respond to various isolated "attacks on the American Embassy complex" in Liberia. The President noted that the deployment of US forces would continue until there was no longer any need for enhanced security at the embassy and a requirement to maintain an evacuation capability in the country.
Central African Republic. On May 23, 1996, President Clinton reported to Congress the deployment of US military personnel to Bangui, Central African Republic, to conduct the evacuation from that country of "private US citizens and certain US Government employees," and to provide "enhanced security for the American Embassy in Bangui."
Rwanda and Zaire. On December 2, 1996, President Clinton reported to Congress that to support the humanitarian efforts of the United Nations regarding refugees in Rwanda and the Great Lakes Region of Eastern Zaire, he had authorized the use of US personnel and aircraft, including AC-130U planes to help in surveying the region in support of humanitarian operations, although fighting still was occurring in the area, and US aircraft had been subject to fire when on flight duty.
Congo and Gabon. On March 27, 1997, President Clinton reported to Congress that, on March 25, 1997, a standby evacuation force of U.S. military personnel had been deployed to Congo and Gabon to provide enhanced security for American private citizens, government employees, and selected third country nationals in Zaire, and to be available for any necessary evacuation operation.
Sierra Leone. On May 30, 1997, President Clinton reported to Congress that on May 29 and May 30, 1997, US military personnel were deployed to Freetown, Sierra Leone, CRS-35 to prepare for and undertake the evacuation of certain US government employees and private US citizens.
Guinea-Bissau. On June 12, 1998, President Clinton reported to Congress that, on June 10, 1998, in response to an army mutiny in Guinea-Bissau endangering the US Embassy, US government employees and citizens in that country, he had deployed a standby evacuation force of US military personnel to Dakar, Senegal, to remove such individuals, as well as selected third country nationals, from the city of Bissau. The deployment continued until the necessary evacuations were completed.
Kenya and Tanzania. On August 10, 1998, President Clinton reported to Congress that he had deployed, on August 7, 1998, a Joint Task Force of U.S. military personnel to Nairobi, Kenya, to coordinate the medical and disaster assistance related to the bombings of the U.S. Embassies in Kenya and Tanzania. He also reported that teams of 50-100 security personnel had arrived in Nairobi, Kenya, and Dar es Salaam, Tanzania, to enhance the security of the US Embassies and citizens there.
Afghanistan and Sudan. On August 21, 1998, by letter, President Clinton reported to Congress that he had authorized airstrikes on August 20th against camps and installations in Afghanistan and Sudan used by the Osama bin Laden. The president did so based on what he viewed as convincing information that the bin Laden organisation was responsible for the bombings, on August 7, 1998, of the US Embassies in Kenya and Tanzania.
Liberia. On September 29, 1998, President Clinton reported to Congress that on September 27, 1998 he had, due to political instability and civil disorder in Liberia, deployed a stand-by response and evacuation force of 30 US military personnel to augment the security force at the US Embassy in Monrovia, and to provide for a rapid evacuation capability, as needed, to remove US citizens and government personnel from the country.
Kenya. On February 25, 1999, President Clinton reported to Congress that he was continuing to deploy US military personnel in that country to assist in providing security for the US embassy and American citizens in Nairobi, pending completion of renovations of the American embassy facility in Nairobi, subject of a bombing in August 1998.
Sierra Leone. On May 12, 2000, President Clinton, "consistent with the War Powers Resolution" reported to Congress that he had ordered a US Navy patrol craft to deploy to Sierra Leone to be ready to support evacuation operations from that country if needed. He also authorized a US C-17 aircraft to deliver "ammunition, and other supplies and equipment" to Sierra Leone in support of United Nations peacekeeping operations there.
Cote d'Ivoire. On September 26, 2002, President Bush reported to Congress "consistent with the War Powers Resolution," that in response to a rebellion in Cote d'Ivoire that he had on September 25, 2002 sent US military personnel into Cote d'Ivoire to assist in the evacuation of American citizens and third country nationals from the city of Bouake; and otherwise assist in other evacuations as necessary.
Horn of Africa Combined Joint Task Force-Horn of Africa was established at Camp Lejeune, North Carolina, on October 19, 2002. In November 2002, personnel embarked on a 28-day training cruise aboard USS Mount Whitney, and arrived in the Horn of Africa on December 8, 2002.
Djibouti. Personnel with Combined Joint Task Force-Horn of Africa operated from the USS Mount Whitney until May 13, 2003, when the mission transitioned ashore to Camp Lemonnier in Djibouti City, Djibouti.
Liberia. On June 9, 2003, President Bush reported to Congress, "consistent with the War Powers Resolution," that on June 8 he had sent about 35 combat-equipped US military personnel into Monrovia, Liberia, to augment US Embassy security forces, to aid in the possible evacuation of US citizens if necessary. The President also noted that he had sent about 34 combat-equipped US military personnel to help secure the US Embassy in Nouakchott, Mauritania, and to assist in evacuation of American citizens if required. They were expected to arrive at the US embassy by June 10, 2003. Back-up and support personnel were sent to Dakar, Senegal, to aid in any necessary evacuation from either Liberia or Mauritania.
Liberia. On August 13, 2003, President Bush reported to Congress, "consistent with the War Powers Resolution," that in response to conditions in Liberia, on August 11, 2003, he had authorized about 4,350 US combat-equipped military personnel to enter Liberian territorial waters in support of UN and West African States efforts to restore order and provide humanitarian assistance in Liberia.
Horn of Africa. On November 4, 2004, the President sent to Congress, "consistent with the War Powers Resolution," a consolidated report giving details of multiple ongoing United States military deployments and operations "in support of the global war on terrorism." These deployments, support or military operations include activities in Afghanistan, Djibouti, as well as Kenya, Ethiopia, Eritrea, Bosnia and Herzegovina, and Kosovo. In this report, the president noted that US anti-terror related activities were underway in Djibouti, Kenya, Ethiopia, Yemen, and Eritrea.
Horn of Africa/East Africa. On May 20, 2005, the President sent to Congress "consistent with the War Powers Resolution," a consolidated report giving details of multiple ongoing United States military deployments and operations "in support of the global war on terrorism," as well as operations in Iraq. US forces are also deployed in Kenya, Ethiopia, Yemen, Eritrea, and Djibouti assisting in "enhancing counter-terrorism capabilities" of these nations.
Uganda. On October 14, 2011, President Obama annouced the US is to deploy 100 combat-equipped military advisors to Uganda to to support regional forces pursuing Joseph Kony and other Lord's Resistance Army
commanders. "The support provided by US forces will enhance regional efforts against the LRA. However, although the US forces are combat-equipped, they will only be providing information, advice, and assistance to partner nation forces, and they will not themselves engage LRA forces unless necessary for self-defense," Obama said.
Source: US Africa Command