First, there is the Israeli blockade of Gaza. Recall that when Israel ended its occupation of Gaza, it did not impose a blockade. Indeed, it left behind agricultural facilities in the hope that the newly liberated Gaza Strip would become a peaceful and productive area.
Instead, Hamas seized control over Gaza and engaged in acts of warfare against Israel. These acts of warfare featured anti-personnel rockets, nearly 10,000 of them, directed at Israeli civilians. This was not only an act of warfare, it was a war crime. Israel responded to the rockets by declaring a blockade, the purpose of which was to assure that no rockets or other material that could be used for making war against Israeli civilians were permitted into Gaza.
Israel allowed humanitarian aid through its checkpoints. Egypt as well participated in the blockade. There was never a humanitarian crisis in Gaza, merely a shortage of certain goods that would end if the rocket attacks ended.
The legality of blockades as a response to acts of war is not subject to serious doubt. When the United States blockaded Cuba during the missile crisis, the State Department issued an opinion declaring the blockade to be lawful. This despite the fact that Cuba had not engaged in any act of belligerence against the United States. Other nations have similarly enforced naval blockades to assure their own security.
Read more here - http://www.nydailynews.com/opinions/2010/06/02/2010-06-02_israel_obeyed_international_law_legally_the_gaza_flotilla_conflict_is_an_openand.html
