Dutch Uncle
* Tertia Optio * Defend the Constitution
Which makes the Hamas security all the more impressive. The Gaza public could not have known without Israeli intelligence also knowing. The puzzle in this is what did Hamas hope to achieve. They had to know holy hell would come at both them and all of Gaza.
Anyway, the existence of a vast rocket supply by Hamas was known.
Hamas massing weapons would have been common. It's not like its news that Hamas conducts terrorist attacks on Israel. Common citizens wouldn't have known how many missiles Hamas was stockpiling, only that they were doing it.
Still, the fact so much material was assembled is, indeed, a major intelligence failure which falls directly into Bibi's lap since he's been Israel's Prime Minister almost continuously since 2009.

