An Israeli citizen perspective:
It was well before my time, but history tells us that President John F. Kennedy ordered a naval blockade of Cuba when it was discovered that Russian missiles capable of targeting US cities were being delivered and activated on Cuban soil. Mind you, not one of these missiles had ever been fired at the United States. Nevertheless, Kennedy considered this act as a direct threat to US national security and ordered the blockade. Every ship approaching Cuba would be intercepted by the US Navy, boarded, and the cargo inspected. Kennedy considered this principle so critical that he risked a nuclear confrontation with the USSR. Khrushchev eventually backed down and all missiles from Cuba were removed. To this day, the US government still imposes an economic boycott on Cuba.
Israel blockaded Gaza in most part due to infiltration suicide-attacks and rocket barrages constantly fired into nearby Israeli towns and villages. No US president would put up with such mayhem inflicted on American citizens, and no Israeli PM would put up with it either. The Egyptian government has also blockaded its portion of the border with Gaza and restricts the ingress/egress of people and materials.
Some have suggested that the blockade is a security failure. This a patently false. Suicide-bombings in Israel are now virtually nil and have been for many years. Rocket and missile parts have been smuggled in through tunnels, but this activity would have increased a thousand fold without the blockade.
The most vocal objection to the blockade resides on foundational pillars of humanitarian-concern and collective-punishment. To some extent, I can agree with these concerns. The problem is, no one has offered a viable/workable alternative. One only has to look at Lebanon and the re-armament of Hizb'Allah to appreciate that the United Nations is totally inept at preventing or even curtailing the delivery of missiles. Hizb'Allah even boasts publicly that its missile inventory has trebled since the UN brokered cease-fire agreement of 2006. The UN sits there and does little to nothing. But when the **** hits the fan, you can bet the farm that they will blame Israel and then scurry away like frightened rodents.
Israel has stated many times that the blockade would be virtually removed if Hamas ceases rocket/infiltration attacks on Israel and the captured Israeli soldier (in captivity since 2006) is released. Hamas says it cannot guarantee the former. Israel has released hundreds of prisoners already to secure the release of Gilad Shalit, but it is never enough. There are always additional insatiable demands.
So I ask. If not a blockade, then what? What mechanism? I want a real/viable proposal that satisfies both major concerns; (a) satisfying Israeli security concerns and (b) increasing the flow of legitimate staples and non-corruptible materials into Gaza. Don't even bother with UN/EU monitors. Neither is particularly competent nor trustworthy.