Who Broke The Ceasefire?

In my attempt to understand the Gaza blockade and assault, I wrote that Hamas broke the ceasefire first. While this is true in some respects, it is misleading in others on close inspection. Wikipedia's summary of the various competing accounts is here. The best full account I have found is in Ha'aretz. It shows how a reduction of the issue can obscure important nuances:

Sources in the defense establishment said Defense Minister Ehud Barak instructed the Israel Defense Forces to prepare for the operation over six months ago, even as Israel was beginning to negotiate a ceasefire agreement with Hamas. According to the sources, Barak maintained that although the lull would allow Hamas to prepare for a showdown with Israel, the Israeli army needed time to prepare, as well. Barak gave orders to carry out a comprehensive intelligence-gathering drive which sought to map out Hamas' security infrastructure, along with that of other militant organizations operating in the Strip.

This intelligence-gathering effort brought back information about permanent bases, weapon silos, training camps, the homes of senior officials and coordinates for other facilities. The plan of action that was implemented in Operation Cast Lead remained only a blueprint until a month ago, when tensions soared after the IDF carried out an incursion into Gaza during the ceasefire to take out a tunnel which the army said was intended to facilitate an attack by Palestinian militants on IDF troops.

On November 19, following dozens of Qassam rockets and mortar rounds which exploded on Israeli soil, the plan was brought for Barak's final approval. Last Thursday, on December 18, Prime Minister Ehud Olmert and the defense minister met at IDF headquarters in central Tel Aviv to approve the operation. However, they decided to put the mission on hold to see whether Hamas would hold its fire after the expiration of the ceasefire. They therefore put off bringing the plan for the cabinet's approval, but they did inform Foreign Minister Tzipi Livni of the developments.

Neither side meant the ceasefire as anything but a lull. We can fight over tiny details, but Israel was intent on refighting this war; and so was Hamas. Who broke the ceasefire becomes less significant once one takes a few steps back.