NAIROBI, Kenya -- Viewing the deadly siege at a shopping mall in Kenya as a direct threat to its security, the United States is deploying dozens of FBI agents to investigate the wreckage, hoping to glean every piece of information possible to help prevent such a devastating attack from happening again, possibly even on U.S. soil.
For years, the FBI has been closely watching the Shabab, the Somali Islamist group that has claimed responsibility for the Nairobi massacre and recruited numerous Americans to fight and die -- sometimes as suicide bombers -- for its cause.
The Shabab has already attacked most of the major actors trying to end the chaos in Somalia -- the United Nations, Uganda, aid groups, the Somali government and now Kenya. The United States has spent hundreds of millions of dollars bankrolling anti-Shabab operations for years, and there is growing fear that the group could turn its sights on U.S. interests more directly, one of the reasons the Obama administration is committing so many resources to the investigation in Kenya.
"We are in this fight together," said Robert F. Godec, the U.S. ambassador to Kenya. "The more we know about the planning that went into this, the way it was conducted, what was used, the people involved, the better we can protect America too."
Less than a day after the standoff ended, more than 20 FBI agents wearing flak jackets and helmets were combing through the wreckage strewn across the steps of the mall. As many as 30 more agents may be on the way, U.S. officials say.
Over the next few days, agents will be collecting DNA, fingerprints and other biometric data, poring through surveillance footage and examining guns, laptops, cameras and computers -- anything to gain insights into how the attack was carried out and the hierarchy, planning and structures behind the group, especially if they have any ties back to the United States.
U.S. officials are mindful that Kenya, one of its closest allies in Africa, has become a precarious buffer zone between the United States and Islamist militants who have declared foreigners legitimate targets in their war.
The U.S. government has learned the hard way what happens if it does not contain groups responsible for faraway attacks. In 1998, the then-relatively unknown group called al-Qaida simultaneously attacked the U.S. embassies here and in Tanzania, killing hundreds and following up a few years later with the terrorist attacks of Sept. 11, 2001.
The Shabab militant group, which has pledged allegiance to al-Qaida and taken responsibility for killing more than 60 civilians at the mall, is considered an especially dangerous threat, because more than two dozen young U.S. men are already learning terrorist tactics in Somalia. So far, this has been a one-way pipeline, but the fear is that some battle-hardened militants could come home with their U.S. passports to strike on U.S. soil.
"You never know when a terrorist attack in a faraway place could be a harbinger of something that could strike at the United States," said Daniel Benjamin, a former Obama administration counterterrorism official.
On Kenya, he said, "It's a country that has a long history of being attacked by terrorists that are of real concern to the United States."
Compounding matters, relations between the United States and Kenya had grown frosty before the attack because Kenya's president has been indicted on charges of crimes against humanity by the International Criminal Court. U.S. officials here were trying to keep their distance from him, but now the two sides must work closely together.
As the mall attack showed, militants would not need to reach the United States to strike hard at U.S. interests. Several Americans were injured in the four-day siege, although none was killed. French, British, Canadians, Chinese, Indians and many others died, most of them Kenyan.
The U.S. government is concerned that the Shabab could target the thousands of Americans living in Kenya, working for companies like General Electric, the embassy or the enormous U.N. office here in the cosmopolitan capital. Tens of thousands of other Americans visit the nation's tourist attractions every year.