For over a decade now Western terrorism experts (and script writers) have predicted that Islamic terrorists would hide bombs inside their bodies in order to avoid detection before the bombers got to their targets (usually high-value individuals). The simplest method to carry a bomb internally is to insert a small (500 gr/a pound of explosives) package up the rectum. A more ambitious method is to perform some surgery to insert the bomb inside the suicide bomber. As early as 2004 the rectum (or “butt bomb”) approach was portrayed in electronic media (series 3, episode 10 of the UK show “Spooks”). Five years later that sort of thing was actually tried, when a Saudi suicide bomber used such a butt bomb to try and kill the Saudi Arabian interior minister. The attack failed.
The 2009 bombing revealed the basic flaw of this technique. An internal bomb would have to blast through the bombers body before it could do some serious damage to the victim. That’s what happened in 2009, where the bomber was blown apart but the nearby victim was only lightly injured. It’s unclear if this was noted when the Taliban tried the same technique against an Afghan politician two years later. Perhaps more explosives were shoved up the bombers butt this time, or it was because the bomber was hugging the victim when the bomb went off, the victim was more seriously injured (mainly by burns from the blast) but survived.
Islamic terrorists are not noted for their scientific prowess, so it’s unlikely that anyone did some basic calculations to determine if a butt bomb would be powerful enough to actually kill the target. Doing live tests is also problematic. In any event, there have been few other instances of butt bombs being used, or even seriously considered.