While the US focuses on the campaign against Iran and the Iranian threats to avenge the death of Al Quds commander Qassem Soleimani, the US suffered an unexpected blow from the Al Qaeda affiliate al-Shabaab, which attacked a US base in Kenya, causing the deaths of 3 Americans.
On December 5, 2020, US Africa Command and Kenya Defense forces (KDF) repelled an attack on Manda Airstrip near the Camp Simba US base in Lamu county, near Kenya's border with Somalia. A US service member and two civilian contractors working for the Department of Defense were killed and two other US Department of Defense personnel were wounded in the attack. Al-Shabaab claimed responsibility for the attack and Kenya's military said it killed at least four terrorists in repelling the attack.
Al Shabaab said the attack was part of its “Jerusalem will never be Judaized” campaign and added that the base was used by both American and Kenyan military personnel, and there were 17 U.S. casualties, nine Kenyan soldiers killed and seven aircraft destroyed. The U.S. Africa Command dismissed the al-Shabaab claims as exaggerated.
An internal Kenyan police report seen by the AP said two fixed-wing aircraft, a U.S. Cessna and a Kenyan one, were destroyed along with two U.S. helicopters and multiple U.S. vehicles at the military airstrip. 
Kenya is a key base for fighting al-Shabaab. US troops began operations at Camp Simba in 2017, performing counter-terrorism and border security operations to aid Kenya. It essentially became a permanent US military installation on August 26, 2019.
The attack on the Manda Airfield has been the worst in its results since the 1998 US Embassy bombing in Nairobi. It was also the Al Qaeda -linked Al Shabaab group’s first attack against U.S. forces in Kenya.
The "Blackhawk down" incident - in October 1993, elite American troops launched a disastrous raid in the Somali capital Mogadishu. Their aim was to capture key allies of the powerful Somali warlord, Gen Mohamed Farah Aideed. But US forces met fierce resistance from Aideed's militia supported by al Qaeda. Two US Black Hawk helicopters were shot down and some 18 Americans were killed. Within six months, the US had withdrawn its forces from Somalia.
Al Shabaab launched two attacks on US and European military targets in Somalia on September 30, 2019. The first attack was on the Belidogle military airstrip which is a base for US and Somalia forces in the Lower Shabelle region in southern Somalia. A suicide car bomber detonated a vehicle packed with explosives at the gate of the Belidogle airstrip. The US military uses the Belidogle airstrip base to launch drones that attack al-Shabab targets and to train Somali troops.
Maj. Gen. William Gayler, U.S. Africa Command director of operations said: "This attack, though ineffective, demonstrates the direct threat al-Shabaab poses to Americans, our allies, and interests in the region."
The second attack was by a suicide car bomber targeting Italian peacekeepers in Mogadishu. The explosion missed a convoy of the European Union peacekeepers but injured Somali civilians who were nearby.
Al-Shabaab al-Mujahedeen is an off-shoot of the former Islamic Courts Union (ICU). Al Shabaab wants to expel the African Union-mandated peacekeeping force AMISOM from Somalia, topple its central government and establish an administration based on its strict interpretation of Islamic sharia law. In early 2008, the U.S. designated Al-Shabaab a global terrorist entity.
The US military estimates that al-Shabaab commands somewhere between 5,000 to 7,000 fighters and still controls about 20% of Somalia's territory mainly rural areas in the south. Al-Shabaab regularly launches bombings and shooting attacks against state targets and civilians. 
Al-Shabaab group poses a serious threat not only to Somalia’s security but also to that of the African continent and the globe at large. It adheres to the same global Islamist ideology as al-Qaeda and has made several public statements pledging allegiance to the group and praising its leaders. Al-Shabaab has links with Boko Haram, Al Qaeda of the Maghreb, Al Qaeda of the Arab Peninsula and an extremist group in Tanzania. The group has issued several threats to strike outside Africa, including American and European targets.
The U.S involvement in Somalia
The Pentagon is running an ongoing mission in which U.S. forces work with African Union and Somali national security forces to fight the al-Shabaab movement.
The US involvement in Somalia intensified in the later years of the Obama administration but has increased significantly since Donald Trump became president, with greater latitude given to local commanders to order airstrikes or take part in raids.
The Trump administration and Somalia’s recently elected president announced in 2017 new military efforts against the al Shabaab group and the White House granted the US military broader authority to carry out strikes in Somalia against Al Shabaab.
The surge in activity came as the US watched for an influx of fighters from ISIS, which has lost almost all its territory in Iraq and Syria. According to the Pentagon, there are approximately 500 U.S. troops in Somalia, up from 50 in the beginning of 2017.
Special operations in Somalia
About 500 Somali Special Forces who make up the battle-tested Danab ("lightning") unit were trained by the United States.
In May 2017, a US Navy Seal was killed and two troops wounded in a raid on an al-Shabaab militant compound in Bariire, in what was the first US combat death in the African country since the 1993 “Black Hawk Down” disaster. Bariire is known as an al-Shabaab stronghold which has been a Launchpad for several major attacks on Mogadishu.
Somali and US commandos stormed on January 18, 2018, a camp of Al-Shabaab in Jame’o village in Middle Shabelle region. In the overnight raid, the commandos killed at least four of the Al Shabaab fighters and rescued child conscripts. U.S helicopters have supported the raid and later evacuated the young recruits.
U.S drone attacks
The airstrikes came as part of an ongoing mission in which US forces are working with the African Union and Somali national security forces to fight the Shabaab movement.
U.S. military's Africa Command head, Gen. Thomas Waldhauser said that since early 2017, the U.S. has increased the number of strikes it conducts. He added that U.S. strikes were providing the space for local forces to grow. AFRICOM said in April 2019 it had killed more than 800 people in 110 strikes in Somalia since April 2017.
Al-Shabaab has been on the offensive since 2019 and increased its attacks on African Union (AMISOM) bases, Somali government facilities and officials and security forces, US and EU forces and targets in neighboring Kenya and Ethiopia.
The high-profile attacks on two foreign targets in Somalia a single day and the attack on the US base in Kenya, proves al Shabaab's enduring power and operational capabilities. The attacks showed that al Shabaab is a well-coordinated force, with a sophisticated intelligence network. 
The US military's Africa Command head, Gen. Thomas Waldhauser, told the Senate Armed Services Committee that " For disrupting extremists, we remain committed to synchronizing our kinetic authorities. Persistent pressure on al-Shabaab, ISIS and al-Qaeda-associated groups remain necessary to prevent this destabilization of African nations. U.S. strategic interests on the continent cannot be solely advanced through the use of military force alone. As such AFRICOM utilizes the military tool in concert with diplomacy and development efforts to help negate the drivers of conflict and create opportunity". In Somalia, we work closely with the Ambassador now permanently stationed in Mogadishu alongside with the USAID Mission Director to help the Somalis assume responsibility for their own security and own prosperity.
Somalia’s security forces are supposed to be taking on more responsibility as the African Union force prepares to withdraw by the end of 2020, but the ongoing attacks indicate that the Somali forces may not be able to hold the gains made by the African Union troops that deprived al-Shabaab of large parts of territory.
 Omar Nor, Radina Gigova and Brad Lendon, Kenya says its military killed 4 terrorists as al-Shabaab claims attack on US base, CNN, January 5, 2020.
 Extremists attack Kenya military base, 3 Americans killed, AP, January 5, 2020.
 Suicide car bomber detonated vehicle packed with explosives at gate of US military base in Somalia, Fox 5, September 30, 2019.
 Extremists launch 2 attacks on military targets in Somalia, abc News, September 30, 2019.
 US General: Strikes in Somalia Won't Stop Al-Shabaab, VOA, February 07, 2019.
 Three Americans killed in Al-Shabaab attack on Kenya military base, the new Arab, January 6, 2020.
 Mary Harper, US Somali operation shrouded in secrecy, BBC, September 30, 2019.
 Transcript: Gen. Thomas Waldhauser and Adm. Craig Faller Remarks at Senate Armed Services Committee Hearing on AFRICOM and SOUTHCOM. AFRICOM and SOUTHCOM 2019 posture testimony to the Senate Armed Services Committee February 7, 2019.