The alleged plot involving six men born outside the United States but living here legally and otherwise is richly detailed in antiterrorist spy craft and less detailed about the plotters' motivation.

Experts in Islam, national security, the Balkans and the Middle East were surprised by the makeup of the group, which consists of four ethnic Albanians born in the former Yugoslavia, one Turk and a U.S. citizen born in Jordan.

"To me, there's this great irony that you've got Albanians who want to attack the U.S. military, based on whatever reasoning," said Robert A. Saunders, an expert on political Islam at the State University of New York in Farmingdale. "Of all the people I talk to in all the world, I haven't found anyone who loves the U.S. more than the Albanian community" because of the U.S.-led intervention against Serbian "ethnic cleansing" in the Albanian enclave of Kosovo.

Saunders, a resident of Monmouth County, lives about 15 miles from Fort Dix, which prosecutors described as the plotters' main target. Beginning in 1999, Fort Dix was a temporary resettlement point for Kosovar refugees fleeing the strife in their homeland.

In announcing the arrests yesterday, the Justice Department described five of the members as "radical Islamists" and the sixth as a conduit for illegal guns.

The criminal complaint cites instances in which the men discussed killing U.S. soldiers and watched training videos in which "known foreign Islamic radicals" urged holy war against the United States, punctuated by shouts of Allahu Akbar, Arabic for "God is great."

"We have to speculate that these [men] probably are being manipulated by the internationalist jihadist ideology: Let's fight the infidel wherever we find him. It's obvious that this is not being done from the standpoint of Albanian nationalism," Saunders said.

Saunders said the phenomenon of homegrown Islamic radicalism is better known as a problem in Britain, Italy, Germany and other European countries.

"You've got second-generation Muslims, they are not immigrants because they were born there, but they are losing their ethnic, cultural and local identities . . . and what they are left with is their religious identity," even if they are not particularly devout, he said. "It's not about religion. It's about politics. It is a political Muslim identity, it's not a religious Muslim identity."

In the case of the New Jersey men, "we may be dealing with a situation in which people are abandoning their old identity and embracing their Muslim identity, and this is how international jihad works," he said.

Charles Kupchan, a professor of international affairs at Georgetown University in Washington, said there are reported pockets of Muslim extremists in the Balkans. "One hears of cells operating in Bosnia, but those consist either of foreigners or Bosnian Muslims, not Albanians," he said.

While emphasizing that he can only speculate because not much is known about the alleged plotters' motives, Kupchan said it was not likely that the planned attack was "payback for something the U.S. did in the Balkans."

"This more likely is a set of extremists motivated by the same concerns about what is going on in the Middle East that have driven Muslim extremism elsewhere," he said.