Keith,

They were using White Phospherous on one of the most densely populated strips of land on earth.

They used cluster bombs and land mines on farmland in south Lebanon.

They often use collective punishment.

The very definition of the current blockade is collective punishment.

Why blockade luxury goods if not to punish the population for voting for Hamas?

All of the above are war crimes.

Why level so many buildings then blockade building materials?

Yes concrete can be used build bunkers. But obviously those bunkers are only useful against massed military attacks. the government of Israel may have a right to defend its population, but the "right" they now defend and claim, the "right" to blockade to maximize the possibility of unfettered attack is beyond absurd.