Are these simply anomalies, bad apples within the greater law-abiding Muslim population in the United States? Or do they indicate that something more sinister needs to be confronted within this population so that the idea of killing innocent people does not become a misguided act of martyrdom?
IN PICTURES: American Jihadis
Answering these questions is one of the most difficult tasks facing the Obama administration. If it decides that some sort of radical form of Islam is making inroads, it risks provoking millions of peaceful Muslims, who may perceive religious persecution. If the administration decides there isn't a problem, it may miss future terrorists.
Here's part of the mind-set that the government is grappling with: When Mr. Shahzad pleaded guilty to planting a weapon of mass destruction in Times Square, he told a federal judge that he viewed himself as a "mujahid, a Muslim soldier."
"I am part of the answer to the US terrorizing the Muslim nations and the Muslim people, and on behalf of that, I'm avenging the attacks," Shahzad said as he explained why he was pleading guilty.
On a more general level, she says, it's not unusual for young Muslims growing up in the US to have an identity issue: Do they wear hair coverings? Do they marry the Muslim boy or girl next door?