I wrote a section about this question, which I do consider highly important, but there wasn't room for it. Here is some of what I wanted to say:
'Max Blumenthal has suggested [http://www.alternet.org/hannibal-directive-how-israels-secret-military-doctrine-deliberately-killed-soldiers-and-massacred?page=0%2C1], based on evidence including testimony from Rafah, that the Hamas attack occurred around 7:30 am, before the start of the ceasefire. But let’s give the IDF the benefit of the doubt and accept the version presented in the Israeli press. (According to Amos Harel and Gili Cohen [http://www.haaretz.com/news/diplomacy-defense/.premium-1.609533], “The official report on the incident appears on computerized operational systems, which would be difficult to falsify due to the many soldiers with access.” This seems slightly credulous, whatever the truth is.) A question arises at once: why were Givati soldiers “out on an offensive patrol” more than one hour into a ceasefire?
The Times of Israel report [http://www.timesofisrael.com/gaza-abduction-comes-to-life-in-recordings/] does not elaborate on this curious detail; in the Israeli context, it hardly requires an explanation. For the IDF has never respected ceasefires. In 1948 Israel broke two UN truces in order to seize the initiative against the Arab forces, and Ben Gurion ordered the army to occupy Eilat in March 1949, after the armistice agreement was signed. (“This was significant for, by seizing Eilat, Israel had driven a wedge between the east and west Arab world,” Ahron Bregman explains, “thus preventing Egypt from having a direct land bridge to Jordan.”) Both the conquest of the Golan Heights in 1967 and the encirclement of the Egyptian 3rd Army in 1973 -- pivotal events in Israeli military history -- were achieved through ceasefire breaches. Reporting on Operation Peace for Galilee in 1982, longtime Mideast correspondent G. H. Jansen observed that “a striking aspect of Israeli military doctrine exemplified in the Lebanese campaign is the military exploitation of a cease-fire. Israel has done this so often, in every one of its wars, that perhaps one must assume that for the Israeli military ‘cease-fire’ only means ‘no shooting’ and is totally unconnected with any freezing of positions on the ground along a ‘cease-fire’ line” (quoted in Noam Chomsky, Fateful Triangle, p. 219).
So it was in Gaza last summer. Here is how John Kerry presented the terms of the truce that was to take effect on Black Friday [http://www.state.gov/secretary/remarks/2014/08/230072.htm]:
"This morning, Israel and the Palestinian factions have agreed that they are now prepared to implement a 72-hour unconditional humanitarian cease-fire. So starting later this morning at 8:00 August 1st, the parties are expected to cease all offensive military activities, and neither side will advance beyond its current locations. They will stay where they are in place. Israel will be able to continue its defensive operations for those tunnels that are behind its lines, and the Palestinians will be able to receive food, medicine, and additional humanitarian assistance, as well as to be able to tend to their wounded, bury their dead, be able to in safe areas travel to their homes, and take advantage of the absence -- hopefully, hopefully -- of violence for these 72 hours."
If Kerry doubted that the violence would indeed come to halt, he had good reason, and himself to blame: allowing Israel to insist on continuing its anti-tunnel operations all but guaranteed that the lull would be extremely short-lived. This wasn’t World War I: destroying tunnels in an urban environment is not the kind of work that will stay contained behind an army’s lines, even if Israel were inclined to take ceasefires seriously. For its part, the leadership of al Qassam Brigades quite reasonably “declared their refusal to tolerate Israeli military maneuvers inside Gaza,” Blumenthal reports. In the event, Givati recon soldiers continued to operate in Rafah, precipitating the encounter that left three of them dead.'
I would add that the IDF's totally unrealistic conception of a ceasefire is further illuminated by Ynet's interview with the Givati commanders:
"In hindsight, we feel frustrated at the way we handled the ceasefire. The ceasefire should not have applied where troops were still present, but rather only in areas the IDF has already left. This is why the enemy allowed itself to rear its head. Had there not been a ceasefire, Benaya might have received authorization to fire a tank shell at the area the suspect was seen in. When my company identified the suspicious motorcyclist, we asked for authorization to fire at him, but did not receive it."