A reader writes:

My guess is that they are cracking down on exports to keep Hamas in theory from purchasing weapons with monies earned from basic capitalism. Never mind that the rockets and other weaponry are being smuggled in free of charge, but my guess is that you will get that answer from Israel if anyone bothered to ask.

Yousef Munnayer cites the 2005 agreement that Israel signed agreeing to up to 400 trucks of exports a day by 2006. Here's what actually happened in graph form (the red line is the agreement; the blue ine is Israel's follow-through):

Gaza Exports

He concludes:

Note the total failure to meet the 150 TPD commitment by 31 December 2005, let alone the 400 TBD by end of 2006, or ever. Keep in mind, Israel's failure to keep this commitment regarding exports precedes Hamas' electoral victory on 26 January 2006 and their solidification of control in the strip in June 2007.

This isn't about Hamas, this isn't about security. This is about punishing the Palestinian people of Gaza by crippling their economy.

Another reader adds:

Isn't the FAR more interesting question: Why does EGYPT blockade Gaza at all? After all, if Egypt maintained no blockade, Israel could hardly enforce one. Why is all the pressure on Israel? We give a huge amount of aid to Egypt, too. Or am I completely missing something? I never, ever see this discussed – MSM or elsewhere. If Egypt is perfectly fine with the blockade, then why does Israel bear the sole blame for it?