STRATFOR ... "From a purely military standpoint, the issue has been Hamas's search for a deterrent to Israeli operations against Gaza. Operation Cast Lead in late 2008 and early 2009 disrupted Gaza deeply, and Hamas found itself without any options beyond attempts to impose high casualties on Israeli forces. But the size of the casualties in Cast Lead did not prove a deterrent.
"Hamas augmented its short-range rocket arsenal with much longer-range rockets. The latest generation of rockets it has acquired can reach the population center of Israel: the triangle of Jerusalem, Tel Aviv and Haifa. However, these are rockets, not missiles. That means they have no guidance system, and their point of impact once launched is a matter of chance. Given these limits, Hamas hoped having a large number of rockets of different ranges would create the risk of substantial Israeli civilian casualties, and that that risk would deter Israel from action against Gaza.
"The threat posed by the rockets was in fact substantial. According to senior Israeli Air Force officers quoted on the subject, Israel lacked intelligence on precisely where the rockets were stored and all the sites from which they might be launched. Gaza is honeycombed with a complex of tunnels, many quite deep. This limits intelligence. It also limits the ability of Israeli airborne munitions from penetrating to their storage area and destroying them. " ...Read more: Gaza Situation Report | Stratfor