This time they can't do this because the operation was largely spontaneous, unlike Operation Cast Lead (in Gaza 2008-2009), so they weren't able to seal the borders.
There's even a NY Times reporter in Gaza, and she's plainly not happy with what she's seeing. The Times even made an “error" yesterday and referred in the headline to the Israeli attack on "civilian buildings." A few hours later they referred to "government buildings.” But today the Times led with the deaths of 11 people, five women, four children (killed by the Israelis Sunday, Nov. 18; the victims are now said to be 12).
Of course, Israel can't be thrilled with this, and they know that in the event of a ground invasion, it'll be scores of civilians killed, not just because they like to kill civilians (which they do) but also because that's the only way the know (how) to fight: destroy everything in your path for miles around. They can't do that now, but also Netanyahu can't risk significant IDF casualties. (It would be a) Disaster with an (Israeli) election looming. So, I still say, no invasion. --Norman Finkelstein
New York Times online, Monday Nov. 19, 2012