Actually for most of us, the category might more appropriately be "travel." This is about the Nigerian guy who trained with Al Qaeda in Yemen, and subsequently roasted himself on board an airliner, trying to ignite an explosive on the approach to Detroit.
Al Qaeda in Yemen has stepped up and claimed responsibility for this guy. They claim his mission was in retaliation for some US activity in Yemen. In other words, the ranking voice for global radical Islam is blaming US policy for this guy. A grievance, if you will.
Historically, radical Islam is not grievance-based. Historically, radical Islamists have cited the Koran as their justification for whatever they did. This grievance business is just an excuse for something they would do anyway. In all their training and indoctrination and what not, they only refer to one book.
This goes back a thousand years to the Barbary pirates. The details of what they pulled off might apall you and gross you out, but they did it for a thousand years. The official US state department inquiry by ambassadors John Adams and Thomas Jefferson turned up one disturbing fact: the Barbary pirates claimed that the justification for their atrocities was clearly written in the Koran. At the time, the US had no foreign policy to grieve.
That’s not to say that all denominations of Islam agree with it. For the moment I’m leaving those distinctions for Obama to figure out. I have other things to do.