Iraqi intelligence has noted some interesting trends in Islamic terror attacks over the last two years (since the collapse of the major Islamic terror groups in the country.) Back in 2008, suicide attacks dropped over 80 percent, and have continued to decline since then. Despite the smaller number of attacks the surviving terrorist groups carry out, the terrorists are still having problems. For example, it's been increasingly difficult to get competent suicide bombers. From 2003-2007, there had been a large supply of foreign suicide bomber volunteers (from Saudi Arabia, Yemen, Jordan, Syria, Libya, Algeria and Morocco). But better security on the Syrian border, and fewer areas where the terrorists could establish safe houses, made it difficult to get the volunteers in and train them. But there were also fewer volunteers. Al Qaeda, and Sunni terrorism took a big image hit in 2005-2008, as it became clear throughout the Moslem would that even Iraqi Sunnis were hostile to the Islamic terrorists. It was also pretty clear that the volunteers were mainly killing civilians. All those videos of dead women and children had an effect. This was often in an indirect way. Many volunteers still wanted to come, but one reason they killed themselves was to win some respect back home. When it became more common, throughout the Arab world, to despise, not honor, the suicide bombers in Iraq, many potential volunteers thought better of dying for the cause (and being held in contempt back home, and bringing shame on his family.)
The shortage has been getting worse over the last two years. Back in 2008, there was evidence that someone was recruiting women for suicide attacks. There was a huge jump in the use of female suicide bombers that year (over 40, compared to 8 for the previous year.) Turns out there were several terrorist cells specializing in recruiting women for this kind of murder. Eventually, all of these groups were taken down. There then followed greater use of the mentally ill as suicide bombers. This did not work out well (it never did), even when the bombs were detonated remotely by someone else. After that, there began the trend (still ongoing) of more remotely controlled bombs. These were harder to get to the target, and jammers made it difficult to set them off. Thus the reduction in terrorist attacks continued.
Afghanistan has similar problems with a shortage of suicide bomber volunteers. There, the chief source is students from religious schools in Pakistan. Often these are teenage kids, but there are not enough of them for all the suicide attacks the local terrorists would like to make. While suicide attacks are widely accepted in the Arab world, Afghans look down on it. But terrorists consider suicide bombing a very effective weapon. To make it work you need volunteers who are reliable and able to learn the techniques of getting to the target undetected, and then actually setting off the bomb. You don't hear much about it, but many (in some situations, over a third) suicide bombers refuse to go through with it. Thus the many "handlers" that work closely with the suicide bomber, until the final moment. The growing shortage of competent volunteers means fewer successful suicide bombing missions, and more captured (or surrendered) bombers means more suicide bombing cells (and their hard to replace management and technical personnel) are destroyed.