Details about a Muslim-American US Army soldier arrested with guns and explosives near Fort Hood, Texas, remain sketchy.

But initial reports suggest that Army Private 1st Class Naser Abdo has confessed to a plot similar to the attack that hit Fort Hood in 2009 – an individual acting alone, based on religious beliefs as well as a personal grudge, intending to do harm on a wide scale. It’s the kind of “lone wolf” scenario US law enforcement officials – and those in Europe, witness Norway massacre suspect Anders Behring Breivik – have been focusing on as a likely source of domestic terrorism.

Here’s what’s known so far: Abdo was arrested Wednesday in a motel room in Killeen, Texas. He had been absent without leave from Fort Campbell, Ky., since the July Fourth weekend.

Tipped off by a gunshop owner in Killeen who became suspicious when Abdo asked about making explosives, agents found firearms and "items that could be identified as bombmaking components, including gunpowder," according to FBI spokesman Erik Vasys.

The “Guns Galore” shop where Abdo made his purchases was the same one where US Army Maj. Nidal Hasan bought the weapons he allegedly used to kill 13 people and wound 32 others at Fort Hood in November 2009. Abdo also went to a military surplus store where he bought uniform items with Fort Hood patches.

"Suffice it to say we're looking into all aspects of Mr. Abdo's life to determine his motivations and intentions,” Mr. Vasys told the Associated Press.

Abdo, who had served about a year on active duty, was an infantry soldier in the 101st Airborne Division at Fort Campbell, about 800 miles from Fort Hood.

Although he once believed that by joining the US Army he could help protect the free practice of Islam in Iraq and Afghanistan, he eventually changed his mind. Based on his religion, Abdo applied for and had been granted conscientious objector (CO) status.

"A Muslim is not allowed to participate in an Islamicly unjust war," he told ABC News last August. "Any Muslim who knows his religion or maybe takes into account what his religion says can find out very clearly why he should not participate in the US military."

Although his request to become a CO had been approved by the secretary of the Army, his separation from the military was delayed when he was arrested in May and charged with having child pornography on his computer. A military Article 32 hearing under the Uniform Code of Military Justice (the equivalent of a civilian grand jury finding) recommended that he be court martialed on those charges. That was when he disappeared from Fort Campbell.

ABC News is reporting that Abdo allegedly planned to bomb a restaurant popular with Fort Hood soldiers then shoot the survivors with a pistol. (Based on information from a defense department official, CNN describes this potential arsenal as “gunpowder, shotgun shells, 18 pounds of sugar, a pressure cooker, four magazines, and ammunition.)

Given the heightened security at Fort Hood since the 2009 rampage in which Hasan is charged, it might have been much more difficult for Abdo to enter the base.

According to the FBI's Vasys, the initial investigation indicates that Abdo was acting alone. "I would emphasize that any threat that Abdo posed is now over," he said.

Many plots involving small groups of conspirators or a lone-wolf individual have been thwarted in recent years, often through the work of paid informants.

But officials increasingly see attacks like the one at Fort Hood – carried out by a single individual driven by ideology and perhaps mental or emotional instability, rather than by a group involved in a conspiracy, as was the case with 9/11 – as the greatest threat to domestic security.

“Our review of attempted attacks during the past two years suggests that lone offenders currently present the greatest threat,” concluded a recent assessment by federal agencies, marked “for official use only” and obtained last month by the AP.

That includes threats against US military installations. Eight such attacks have been planned or carried out in the past two years.

Abdo is expected to be charged under federal law.