Nearly everyone acknowledges Israel's right of self-defense. How could they do otherwise? It is in the UN Charter. Article 51 provides:

"Nothing in the present Charter shall impair the inherent right of individual or collective self-defense if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security."

Thus this right can only be relied upon and acted upon until such time as "the Security Council has taken measures necessary to maintain international peace and security". Such measures take the form of resolutions. But surely as long as such measures are intended to maintain peace and security, it matters not whether they have succeeded. And if they haven't succeeded then surely the right of self-defense may still be resorted to.

Secondly, the right of self-defense does not prevent the Security Council from acting to maintain or restore peace and security. Obviously the Security Council could deem it necessary to oppose actions taken in self-defense if it deems such acts are detrimental to peace and security. So much for the right of self-defense.

Thus if Hamas stops shooting, there is no need for Israel to act in self-defense. Not exactly. Israel has the right to prevent Hamas from acquiring threatening weapons regardless if Hamas has stopped shooting.

The Report of the Secretary-General's Panel of Inquiry on the 31 May 2010 Flotilla Incident found:

"The fundamental principle of the freedom of navigation on the high seas is subject to only certain limited exceptions under international law. Israel faces a real threat to its security from militant groups in Gaza. The naval blockade was imposed as a legitimate security measure in order to prevent weapons from entering Gaza by sea and its implementation complied with the requirements of international law."

Since it is "a legitimate security matter" to prevent weapons from entering Gaza, isn't it such a legitimate security measure to seek out and destroy the weapons that have gotten through? I think so.

Whenever the Arabs want a ceasefire due to the fact that they are losing the war, they simply ask the Security Council for a ceasefire resolution and once obtained, Israel must stop fighting. She is thereby denied the fruits of victory. This is the way it has always been.

But this scenario does not prevent Israel from maintaining the blockade. Israel could rightfully argue that, ceasefire or not, she has the right to seek out and destroy the weapons which they currently have.

Though Israel has vacated Gaza, the international community still considers it an occupier of Gaza. As such Israel should have the right to reassert control and seek out the terrorists and their weapons out much in the same way she went back into Judea and Samaria after Intifada II.

It is wrong to define such actions as an "invasion."  Gaza is not a sovereign territory. According to the UN it is an occupied territory. Occupation law entitles Israel to maintain peace and security. In fact it imposes a duty to do so.