Given Minneapolis Somali indictments and other recent news, how should we think about potential terrorism in U.S.?

Add the terrorist indictments in Minneapolis this week to other recent threatening incidents and you come up with some seriously shaken assumptions about America's domestic security.

One assumption was that Europe was more vulnerable to homegrown terrorists than we were. Train bombings in London in 2005 and Madrid in 2004 seemed to prove the point. Further, polls suggested that Muslims in the United States were more assimilated into the middle class and more satisfied with their lives than their European counterparts.

Now, though, the evening news and the morning paper bring a rash of worries about America's homegrown terrorists. And heated debate on the topic rages through the talk shows and the blogosphere.

There should be debate. Some of the old assumptions were flawed in the first place. But some conclusions people are drawing now are flawed too.

The full stories of the cases behind this fresh controversy have yet to be told. The only clear point is that they are as politically and psychologically complex as any issue could be. Here they are in summary:

• Terrorism charges [PDF] were filed in Minneapolis on Monday against eight men who are accused of various roles in the recruiting of some 20 local Somalis to fly to their homeland and train with al-Shabaab, an organization the U.S. government says is tied to al-Qaida and international terrorism. In all, 14 men have been indicted in the case, some of whom fled the United States months ago.

• The murder of 13 people on Nov. 5 at Fort Hood, Texas, set off speculation that the accused killer, Maj. Nidal Malik Hasan, is an Islamic terrorist. To be clear, terror charges have not been filed in the case. And there is reason to argue that Hasan had simply and tragically cracked under pressure. But Sen. Joseph Lieberman, I-Conn., is one of several U.S. lawmakers citing the massacre as reason to push for an investigation into the "larger pattern of homegrown terrorism that has emerged over the past several years."

• In an alleged large-scale bomb plot against New York City, authorities say Najibullah Zaza, a Colorado airport van driver, received explosives training from al-Qaida in Pakistan and brought deadly skills back home to kill Americans. An Imam in Queens has been accused of tipping off Zaza about the undercover investigation into his activities and then lying to the FBI about it. The men have pleaded not guilty.

Added together, the cases make for a troubling picture that should be taken seriously. 

But they also should be seen distinctly because they pose different levels of danger to the United States, said Daniel Byman,  director of the Security Studies Program and the Center for Peace and Security Studies at Georgetown University.

The Fort Hood case
The nation knows from tragic example — take the bombing of the Federal Building in Oklahoma City or the massacres at Columbine High School and Virginia Tech — that cases of lone killers on the rampage can be the most difficult to prevent.

But if it turns out that Hasan was an angry man who snapped and not part of a larger group, his case is the least worrisome in terms of terrorist threats, Byman wrote in a recent National Journal discussion of homegrown terrorism.

Angry individuals regularly do horrible things and kill significant numbers of people, Byman said. But if they are not tied to a broader group, "we rarely need to fear a broader spree of killings and follow on attacks."

The Somali case
The radicalization of some 20 Somali Americans is more worrisome.

Generally it is true that Muslim and Arab Americans are more integrated into the middle-class mainstream than is the case in Europe. A poll of Muslim Americans conducted in 2007 by the Pew Research Center found that large majorities rated their communities as excellent or good and lived on incomes comparable to the nation as a whole. Those polled in the United States rejected Islamic extremism in larger margins than did Muslim minorities in Western European countries.

The assumption that America is less vulnerable than Europe still holds, Byman said in an interview with MinnPost.

"But the difference is less than we assumed," he said. "There are exceptions."

Somali Americans are among the most recent arrivals in the United States. Their ranks in Minnesota include professors, doctors and lawyers. You only need to walk streets, stores and college campuses in the Twin Cities to know they have blended deep into the local culture in a relatively short time.

But it can take decades for an immigrant community to recover from wrenching change and truly feel at home in a new home, Byman said.

On top of that considerable challenge, Somali Americans were torn over U.S. policy toward conflict in their homeland. After decades of inter-clan violence and anarchy in Somalia, a U.S.-backed Transitional Federal Government had formed and tried to take charge in 2006. It met intense resistance from a coalition of Islamic groups. Ethiopian troops surged in to back the Transitional Government.

And thousands of Somalis in Minnesota were incensed.

Advocates for both sides in Minnesota
Minnesota is home to advocates for both sides of the conflict. So the reaction varied. Without question, though, there was heated opposition to Ethiopian boots on Somali soil. I heard it in the mosques, the student centers and the coffee houses while covering the Somali community during 2007.

Now, authorities have confirmed the common street wisdom that young Somali men recruited here to fight in their homeland thought they were going to save their country from Ethiopian invaders.

Authorities also say there is no evidence they planned to come back and kill Americans. Like Arab Americans who are upset with U.S. policy toward the Israeli-Palestinian conflict, the Somalis have expressed their dissent in non-violent ways.

Still, the potential for a more militant response is a legitimate concern, Byman said.

"It's an extremely small portion of the Somali American community that is actively involved in this, and then it's an even smaller portion that goes to Somalia, and a smaller portion yet that somehow links up to the global jihad," he said. "But that small number can be very dangerous . ... There is a concern that these people might be radicalized on their own when they come back, just angry because they feel the U.S. is supporting the killing of their kin."

Al-Qaida has exploited such resentment to find recruits in Europe, and it could try to do the same here. But, at this point, "could" is the operative word. No official is saying that actually has happened.

The Zazi case
The most threatening case is the foiled plot to bomb trains and other public facilities in New York this year, Byman said.

So far, Zazi stands accused largely alone although authorities allege he had at least one sympathizer who sought to shield him from police. In contrast, the Somali Americans are accused of operating as part of a larger functioning international network.

The dramatic difference, Byman said, is that Zazi returned to America after training abroad and directly prepared to kill Americans.

"That's a big leap," Byman said. "Zazi came to kill people, and he knew what he was doing. He was a skilled individual. We have seen in the past that a few skilled individuals are often very good at hooking up with unskilled locals and acting as force multipliers."

Zazi knows this country well and authorities say he is linked to the al Qaida core. He was preparing to act strategically, not rash and impulsively like Hasan.

The crucial question now is whether "Zazi was kind of a one off — was he just the one guy or are there others," Byman said.

For that matter, the Somali situation will bear watching for years to come too. Top FBI officials said in Minneapolis on Monday that their investigation isn't over. 

So we still can't know, Byman said, "Are we going to look back in 10 years and say the signs were all there? Or will we look back and say this was a danger that never became reality?"

Sharon Schmickle covers science, international affairs and Greater Minnesota.