Leading article: The true picture of the brutal Gaza invasion comes into focus

It was the most terrible episode to emerge from a terrible war.

During the Israeli assault on Gaza in January 2009, Palestinian civilians in the Zeitoun area of Gaza City were instructed by the Israeli Defence Force (IDF) to take refuge in a local warehouse for their own safety. Yet that warehouse was subsequently hit by Israeli missiles. Some 21 Palestinians were killed, all from the same extended family.

The initial Israeli investigation of the incident, ordered by the IDF chief of staff, cleared the commanders on the ground of any wrongdoing. But now, almost two years on, senior army officers are under investigation again. Air force officers are reported to have testified that the senior commander who ordered the warehouse attack, Ilan Malka, was told that there were civilians in the area.

We must await the result of this investigation. Yet there are already some lessons to be drawn. If Israeli officers did not know there were civilians in the warehouse, they most certainly should have, since their own troops had been shepherding Palestinian civilians to that location. If nothing else this was a disgraceful failure of communication by the IDF. The picture of what actually took place on that day – compiled by the courageous Israeli human rights campaign group Breaking the Silence – also suggests a profound lesson. It would appear that Palestinian civilians who had left the warehouse to collect firewood were spotted by an Israeli pilotless drone and wrongly identified as armed militants. It was this information alone that resulted in the attack being launched. It is scarcely believable that the Israeli military called in an air strike in a civilian area on the basis of nothing more than a blurry video from an overhead drone.

This incident needs to be seen in the context of the criticisms made of the Israeli military by the United Nations' Goldstone report in September 2009. This accused the IDF of using excessive firepower and disregarding the likelihood of civilian deaths in Gaza. The Israeli military was said to have engaged in the collective punishment of Palestinian civilians through the deliberate destruction of water sanitation systems and residential buildings. Goldstone also said that attacks on Gaza City's Al Quds Hospital and an adjacent ambulance depot might constitute war crimes. This interpretation of IDF conduct was supported by testimony obtained from low-ranking frontline soldiers by Breaking the Silence, which highlighted dangerously loose rules of military engagement and the use of Palestinian civilians as human shields.

The UN report was instantly dismissed by the Israeli state as "biased" and "ludicrous". And groups such as Breaking the Silence have been slurred and intimidated within Israel. Yet the external pressure generated by the Goldstone findings appears to have played a part in prompting this fresh IDF investigation. And it is through the efforts of groups such as Breaking the Silence that the outside world has been able to build up a picture of what actually took place in Gaza.

Israel does itself no favours by instinctively dismissing all criticism of the conduct of its military as dishonest or unwarranted. The Israeli Defence Force often cites its motto of "purity of arms". Rather than attacking the efforts of those who seek to hold it to this high standard, the Israeli military should welcome them.