The Americans leadership said it is not sustainable. This didn't mean that the Americans thought that Israel could not keep it up. This meant that America would take steps to end it at some point. The message to Israel is FIX IT and FIX IT SOON. Israel says that Hamas is dedicated to the destruction of Israel. It says so right in their charter. Hamas leaders, two years ago, said that they would be willing to accept the Saudi plan, or a peace plan based on the 1967 borders. Israel made sure not to pursue this offer, since any peace plan would end settlement expansion and erase all that settlement expansion over the past years and decades. Israel does not want peace. It is political suicide for the Israeli that makes the deal. Hamas does not pursue peace when there is no chance of it since it would make them appear weak to Israel as well as being a waste of time. Hamas should not be discounted from the peace process. After all, it was Israel that give rise to Hamas (as well as Hizbollah) in the 1980's due to the oppressive Israeli policies.
UN: Gaza could be 'uninhabitable' by 2020 if trends continue (AP)
from the article: Israel faces growing world pressure to lift Gaza blockade