National security officials have long feared the emergence of a new breed of American militants who would raise little suspicion as they move in and out of the country carrying out the aims of terrorist groups like al Qaeda.
"It's the manifestation of a problem that the counterterrorism community has been worried about all along," said CBS News national security analyst Juan Zarate, a top counterterrorism official in the Bush administration. Their worries center on "a radicalized individual who decides to take matters into his own hands."
Abdulhakim Muhammad, who grew up in Memphis, Tenn., converted to the Islamic faith, changed his name from Bledsoe, and traveled to Yemen in 2007. He was later arrested for overstaying his visa and deported back to the U.S., where he slid quietly into life in Little Rock, Ark., apparently unnoticed by U.S. law enforcement.
Muhammad was charged with killing Pvt. William Andrew Long, 23, of Conway, Ark., who had just completed basic training and was volunteering at the west Little Rock recruiting office before starting an assignment in South Korea. He was shot dead on June 1 while smoking a cigarette outside the building. A fellow soldier, Pvt. Quinton I. Ezeagwula, 18, of Jacksonville, Ark., was wounded. And an FBI-Homeland Security intelligence assessment document suggested Muhammad may have considered targeting other locations, including Jewish and Christian sites in several eastern U.S. cities.
Muhammad, 23, told The Associated Press in a jail cell interview last week that the shootings were an "act for the sake of God, for the sake of Allah, the Lord of all the world, and also a retaliation on U.S. military."
Former West Point researcher and jihadist expert Jarret Brachman calls the Arkansas killing a landmark case and "a giant step forward for the global jihadist movement." Brachman, who wrote a book on global jihad, said Muhammad's case proves that the U.S. can no longer pretend that violent jihadism is a foreign phenomenon.
"It is being born and bred here on American soil," he said. "The seeds have all been sown over the past few years, between Iraq and Afghanistan on our side, and the increased propaganda and increased jihadi education materials on their side."
While Western Europe has long grappled with homegrown terrorists, the U.S. has only recently begun to see instances of American-born-and-raised citizens acting on Islamic terrorist motivations. Counterterror officials say Muhammad succeeded where other homegrown militant plotters have largely failed.
Earlier this year four Muslim ex-convicts were arrested in New York for allegedly plotting to bomb synagogues and shoot down military planes. While federal authorities foiled the plan, the incident inflamed concerns about the spread of Islamic extremism in prisons.
That fear has been exacerbated in recent months by the debate over transferring suspected Islamic terrorists from the Guantanamo Bay detention center to U.S. prisons.
Muslim converts who bonded in prison were also linked to a 2005 plot to launch jihad-style attacks against Jewish and military targets in California. Law enforcement authorities investigating a string of gas station robberies uncovered the plan when they found a list of targets including three California National Guard facilities, the Israeli Consulate in Los Angeles and several synagogues.
In some ways, violence plotted or committed by a lone gunman poses a greater threat than the actions of a group of plotters because there are no conspirators to help expose or allow for infiltration of the plot, said Zarate, now a senior adviser at the Center for Strategic and International Studies.
At the same time, he said, an individual's attack may not have the same impact or widespread damage as one planned by a group against multiple, strategic targets.
Recent attacks by non-Muslims - including (left) and - have garnered nationwide attention.
"There are very few ways to prevent them ... short of assigning a police officer to every person in America," said the Southern Poverty Law Center's Mark Potok.
Counterterrorism officials warn that unless individuals attract attention either through criminal behavior or even threat-laced Internet postings, U.S.-born radicals - particularly those operating alone - could go unseen until they take action.
"One of the scariest things is that we don't have a profile for how someone becomes radicalized," said counterterrorism expert Matthew Levitt. "It's different for everybody."
"It can happen on the Internet. It can happen in prison. It can happen in a mosque," said Levitt, who formerly worked with the FBI and Treasury Department. "There are different ways it manifests itself and that demonstrates how serious a problem it is."
Muhammad, in recent comments, denied he was radicalized in Yemen, a lawless, violence-wracked country where extremists are known to seek safe haven. In his interview with the AP, Muhammad said he acted out of revenge for claims that U.S. troops had desecrated copies of the Quran and killed or raped Muslims.
Levitt, co-author of a recent study on radicalization by the Washington Institute for Near East Policy, said the U.S. needs to ensure that agencies work to maintain positive relations with the Muslim community. He and others point to Britain's efforts to counter extremist messages with more moderate Islamic voices, particularly within those communities.
"We can create space for lots of multiple competing voices - religious voices, secular voices," said Levitt. "The more voices out there, the more there will be competition for people who may be upset or frustrated about something but need not necessarily express themselves in a violent nature."
By Associated Press Writer Lolita C. Baldor