Let us assume for a moment that the parcel bombs sent to Jewish targets in Chicago were viable devices and this was a real attack by anti-Jewish, and probably Islamic, terrorists. There are other possible explanations, but it is not improbable this was a real attempted attack.

We are looking at low level, workaday terrorism. Parcel bombs were not infrequent in the UK in my youth, and the Unabomber caused extraordinary levels of alarm in the United States. Any loss of life is deplorable, but the scale of this threat appears to have been small.

http://uk.reuters.com/article/idUKTRE69S37420101030?pageNumber=1

It is hard to believe that a parcel bomb would have killed more than a couple of people – there have been a large number of parcel bombs used over decades, and they do not cause mass casualties. Now two or three dead or injured people is too many, but the worldwide media coverage is completely disproportionate to the threat – if they covered every two or three actually, not potentially, dead Afghans in this depth, they would never cover anything else.

It is of course possible that the media coverage was the aim rather than two or three unfortunate people in Chicago. The easy and extremely detailed tip off from the Saudi security services is very interesting. If publicity rather than death was the aim, that rather widens the field of people who might have been behind it.