While putting few U.S. troops at risk, the United States is playing a growing role in Africa's military battles, using special forces advisers, drones and tens of millions of dollars in military aid to combat a growing and multifaceted security threat.
Once again, the focus is Somalia, the lawless nation that was the site of America's last large-scale military intervention in Africa in the early 1990s. By the time U.S. forces departed, 44 Army soldiers, Marines and airmen had been killed and dozens more wounded.
This time the United States is playing a less visible role, providing intelligence and training to fight militants across the continent, from Mauritania in the west along the Atlantic coast, to Somalia in the east along the Indian Ocean.
The renewed focus on Africa follows a series of recent and dramatic attacks.
In August, a hard-line Islamist group in Nigeria known as Boko Haram bombed the U.N. headquarters in the capital, Abuja, killing 24 people. A year earlier, militants from the Somali group al-Shabab unleashed twin bombings in Kampala, Uganda, that killed 76. And a Nigerian man tried to blow up an airliner over Detroit on Christmas Day 2009 during a flight that originated from Lagos, Nigeria.
Most worrisome to the United States is al-Shabab, an al-Qaida-linked group in Somalia that has recruited dozens of Americans, most of Somali descent.
"If you ask me what keeps me awake at night, it is the thought of an American passport-holding person who transits through a training camp in Somalia and gets some skill and then finds their way back into the United States to attack Americans," Gen. Carter Ham, the commander of the U.S. Africa Command, said in Washington this month. "That's mission failure for us."
U.S. and European officials also worry that AQIM _ an al-Qaida group that operates in the west and north of Africa _ is working to establish links with Boko Haram and al-Shabab, the Somali insurgent group.
"I think the security threats emanating from Africa are being taken more seriously than they have been before, and they're more real," said Jennifer Cooke, the director of the Africa program at the Washington-based Center for Strategic and International Studies.
The U.S. is conducting counterterrorism training and equipping militaries in countries including Algeria, Burkina Faso, Chad, Mali, Mauritania, Morocco, Niger, Nigeria, Senegal and Tunisia to "preclude terrorists from establishing sanctuaries," according to the U.S. Africa Command.
In Somalia, the U.S. helps support 9,000 troops from Uganda and Burundi to fight militants in Mogadishu, the Somali capital. In June, the Pentagon moved to send nearly $45 million in military equipment, including four drones, body armor and night-vision and communications gear, for use in the fight against al-Shabab.
The U.S. also announced this month it is sending 100 advisers, most of them special forces, to help direct the fight against the rebel Lord's Resistance Army in Central Africa and efforts to kill or capture its leader, Joseph Kony, who is wanted by the International Criminal Court. In Libya, U.S. fighter planes helped rebels defeat former dictator Moammar Gadhafi.
In the latest attack against Africa's militants, Kenya deployed troops this month into southern Somalia to fight al-Shabab insurgents. The U.S. says it is not aiding Kenya's incursion, but America has given Kenya $24 million in aid this year "to counter terrorists and participate in peacekeeping operations," the U.S. Embassy said.
The U.S. government "has had a burr under its saddle about Somalia" for years, dating to the 1993 downing of two U.S. helicopters over Mogadishu in a battle that became known as Black Hawk Down, said John Pike of the Globalsecurity.org think tank near Washington. Eighteen U.S. troops were killed.
At that time, Washington had deployed thousands of troops to combat a famine, but the mission escalated into a hunt for warlords.
These days, only a handful of U.S. troops are involved directly in Somalia _ special forces troops who enter on kill missions. In 2009, Navy SEALs targeted and killed al-Qaida operative Saleh Ali Saleh Nabhan in a helicopter raid. The Americans jumped out of the helicopters, grabbed Nabhan's body from his bullet-riddled convoy and flew off. The corpse _ like Osama bin Laden's two years later _ was buried at sea.
Pike, who monitors defense issues, said the Pentagon has ramped up operations in Africa tremendously since the time of former Defense Secretary Donald Rumsfeld, who didn't see Africa as being in America's strategic interest.
"The U.S. has really developed an interest in Africa that we just have never seen before," Pike said.
"Between all the goings and comings in the Horn of Africa and all this snake-eater (special forces) Sahara stuff ... it's all over the place," Pike said. "Since I think an awful lot of it is being run out of Special Operations Command and out of (the CIA), I think it probably far larger than anyone imagines."
U.S. drones launched from the Seychelles islands in the Indian Ocean also provide intelligence, and the pilotless planes are capable of being armed.
Al-Shabab counts 31 American citizens among its ranks, a U.S. official in Washington told The Associated Press. They're mostly American-Somalis who left the U.S. to join the group. The U.S. official, who spoke on condition of anonymity to discuss sensitive intelligence matters, said foreign fighters among al-Shabab's ranks want to attack Western targets.
Intelligence has revealed sophisticated plans by al-Shabab to attack targets in Europe, the official said, but the operations have been disrupted by the recent stepped-up fighting in Somalia.
Ugandan and Burundian troops fighting al-Shabab militants in Mogadishu as part of an African Union force have pushed back the insurgents in recent months and now control most of the capital. The Kenyan incursion has forced al-Shabab to fight on its southern flank as well.
Though the Kenyan invasion appears to further the U.S. goal of pressuring al-Shabab, U.S. officials say the American military is not providing assistance.
"The United States has supported Kenyan efforts to improve its ability to monitor and control often porous land and maritime borders and territory exploited by terrorists and illicit traffickers, particularly along its border with Somalia," said Katya Thomas, a spokeswoman at the U.S. Embassy in Nairobi.
But, she added: "The United States did not encourage the Kenyan government to act, nor did Kenya seek our views. We note that Kenya has a right to defend itself against threats to its security and its citizens."
Some aspects of Kenya's military adventure appear poorly thought out. Troops moved in just as seasonal rains began and are now bogged down in the mud _ a literal reminder of the potential quagmire for countries that intervene in Somalia, whose last nationwide leader was overthrown in 1991.
A paper published by the U.S. Army examining the ill-fated U.S. mission in Somalia in the 1990s concluded that "the chaotic political situation of that unhappy land bogged down U.S. and allied forces in what became, in effect, a poorly organized United Nations nation-building operation."
It was a 2006 invasion of Somalia by Ethiopia that gave rise to the militants now known as al-Shabab.
"That's the problem with Somalia, there is just no easy answer," said Cooke, the analyst. "The problem is so huge and multi-faceted that tackling one aspect of it, i.e., beating back al-Shabab, just can't fix it. Part of the problem is that the government we have invested in as our key partner in Somalia is a fiction of a government, and so Kenya can try to create some space, but there is nothing to fill that."
The chairman of the Pentagon's Joint Chiefs of Staff, Gen. Martin E. Dempsey, told the House Armed Services Committee this month that the U.S. must remain active in Africa because terrorists are networked globally.
"One of the places they sit is Pakistan. One of the places they sit is Afghanistan. One of the places they sit is the African continent," Dempsey said.
Associated Press reporter Lolita Baldor in Washington contributed to this report.
(This version CORRECTS death toll from Abuja bombing to 24)