WASHINGTON - A Somalian American man, who died in what is believed to be the first suicide bombing carried out by a U.S. citizen, appears to have been "radicalized" in the United States, FBI Director Robert Mueller said yesterday.

The suspect, identified in news reports as Shirwa Ahmed of Minnesota, died in the bombing in northern Somalia in October. He was recruited while in the United States, and other Somalian Americans may have been "radicalized" as well, Mueller said.

The recruiting in the United States "raises the question of whether these young men will one day come home, and, if so, what they might undertake here," Mueller said in a speech to the Council on Foreign Relations, a research group.

Since the terror attacks of Sept. 11, 2001, young men from communities in the United States have been recruited to travel to other countries, including Iraq, Yemen, and Afghanistan, Muller said. They were sought out to participate in fighting or suicide bombings, he said.

The attacks in Mumbai, India, in November were a reminder that extremists "with large agendas and little money" can use basic weapons to "maximize their impact," Mueller said. The attacks on the Oberoi and Taj Mahal Hotels, a main train station, and a Jewish center, all of which killed 164 people, raise the possibility of similar incidents in this country, Mueller said.

The FBI is increasingly concerned about "pockets of people" around the world that identify with al-Qaeda, Mueller told the group. Authorities also should focus on less well-known groups - "homegrown terrorists" - and extremists who do not need visas to travel to the United States, he said.

"We need to know where the threat is moving, and we need to get there first," he added.

Authorities have said they are monitoring Somalian Americans who left Minneapolis and other U.S. cities during the last year and a half. Some may have traveled to Somalia to join al-Shabaab, an extremist Islamic organization linked to al-Qaeda and considered a terrorist group by the United States.

The FBI and the Department of Homeland Security previously said they investigated the threat of an attack by al-Shabaab that could have been directed at Washington, possibly coinciding with President Obama's inauguration last month.

The FBI returned the remains of Ahmed to his family in the Minneapolis-St. Paul area, the Washington Post reported. Members of the community where he lived said Ahmed, a naturalized U.S. citizen, blew himself up in the October bombing in Somalia.

"It appears that this individual was radicalized in his hometown in Minnesota," Mueller said.