Never mind.  I think I found the answer in this July 18, 2005 interview with Pape:

Al-Qaeda appears to have made a deliberate decision not to attack the United States in the short term. We know this not only from the pattern of their attacks but because we have an actual al-Qaeda planning document found by Norwegian intelligence. The document says that al-Qaeda should not try to attack the continent of the United States in the short term but instead should focus its energies on hitting America's allies in order to try to split the coalition.

What the document then goes on to do is analyze whether they should hit Britain, Poland, or Spain. It concludes that they should hit Spain just before the March 2004 elections because, and I am quoting almost verbatim: Spain could not withstand two, maximum three, blows before withdrawing from the coalition, and then others would fall like dominoes.

That is exactly what happened. Six months after the document was produced, al-Qaeda attacked Spain in Madrid. That caused Spain to withdraw from the coalition. Others have followed. So al-Qaeda certainly has demonstrated the capacity to attack and in fact they have done over 15 suicide-terrorist attacks since 2002, more than all the years before 9/11 combined. Al-Qaeda is not weaker now. Al-Qaeda is stronger.

It seems to me, the fundamental strategic raison d'être of suicide bombing is indeed to compel foreign occupiers to leave the bombers' homeland.  However, in the case of "Islamic militantism", there are two twists:

• the instigators and organizers of these attacks, their "executive producers", so to speak, often use religion to recruit bombers and to give the attacks a supra-political sex appeal for these young men and women


• through the use of religion, even people who are not part of the same political community (in the conventional, non-Islamicist sense) as those in the lands being occupied can still identify with them politically, since as Muslims they are part of the same ummah as the people in those lands (my understanding is that Islam does not really distinguish between the political and religious basis of the community of Muslims, and as such under an extreme interpretation, all Muslims could be viewed as being "occupied" by Americans on the Arabian peninsula and in Iraq, by Israelis in Palestine, by Indians in Kashmir, and so on.)

So, the primary cause of suicide by bombing may in fact be political (i.e. the desire to expel occupiers from one's homeland), but the abuse of formal religion intensifies and broadens the appeal of this strategy significantly.

Point n'est besoin d'espérer pour entreprendre, ni de réussir pour persévérer. - Charles le Téméraire