Israel has tried to take the initiative in the propaganda war over Gaza but, in one important instance, its version has been seriously challenged.
The incident raises the question of how to interpret video taken from the air.
Israel released video of an air attack on 28 December, which appeared to show rockets being loaded onto a lorry. The truck and those close to it were then destroyed by a missile. Click here to watch the Israeli footage of the truck being attacked.
This was clear evidence, the Israelis said, of how accurate their strikes were and how well justified. A special unit it has set up to coordinate its informational plan put the video onto YouTube as part of its effort to use modern means of communications to get Israel's case across.
The YouTube video has a large caption on it saying "Grad missiles being loaded onto the Hamas vehicle." As of Saturday morning UK time, more than 260,000 people had watched it.
It turned out, however, that a 55-year-old Gaza resident named Ahmed Sanur, or Samur, claimed that the truck was his and that he and members of his family and his workers were moving oxygen cylinders from his workshop.
Ahmed Sanur is challenging Israel's claim that rockets were targeted
This workshop had been damaged when a building next door was bombed by the Israelis and he was afraid of looters, he said.
The Israeli human rights group B'Tselem put Mr Sanur's account on its website, together with a photograph of burned out oxygen cylinders.
Mr Sanur said that eight people, one of them his son, had been killed. He subsequently told the Israeli newspaper Haaretz: "These were not Hamas, they were our children... They were not Grad missiles.".
The Israeli response was that the "materiel" was being taken from a site that had stored weapons. The video remains on You Tube.
But the incident shows how an apparently definitive piece of video can turn into something much more doubtful.
B'Tselem said these cannisters were near the destroyed truck
It is reminiscent of an event in the Nato war against Serbia over Kosovo in 1999. In that case, a video taken from the air seemed to show a military convoy which was then attacked.
On the ground however it was discovered that the "trucks" were in fact tractors towing cartloads of civilian refugees, many of whom were killed.
The Israeli propaganda effort is being directed to achieve two main aims.
The first is to justify the air attacks. The second is to show that there is no humanitarian calamity in Gaza.
Both these aims are intended to place Israel in a strong position internationally and to enable its diplomacy to act as an umbrella to fend off calls for a ceasefire while the military operation unfolds.
Israel has pursued the first aim by being very active in getting its story across that Hamas is to blame. The sight of Hamas rockets streaking into Israel has been helpful in this respect.
It has also allowed trucks in with food aid and has stressed that it will not let people starve, even if they go short.
Israel appears to think its efforts are working.
One of its spokespeople, who has regularly appeared on the international media, Major Avital Leibovich, said: "Quite a few outlets are very favourable to Israel."
Ban on foreign media
Israel has bolstered its approach by banning foreign correspondents from Gaza, despite a ruling from the Israeli Supreme Court.
The Arab television news channel Al Jazeera is operating there and its reports have been graphic and have affected opinion across the Arab world. The BBC also has its local bureau hard at work.
But the absence of reporters from major organisations has meant, for example, that Mr Samur's story has not been as widely told as it probably would have been, or his account subject to an on-the-spot examination.
Meanwhile Israel has received good coverage of the threats and damage to its own towns and communities.
Whether Israel retains any propaganda initiative is not all certain. Pictures of dead and wounded children have undermined its claim to pinpoint accuracy and the longer this goes on, the greater the potential for world public opinion to swing against it, with diplomatic pressure building for a cessation.
Its presentational problems would be hugely increased if it engaged in a ground operation, which would bring with it more pictures of death and destruction.
Update: several readers have e-mailed to ask whether I believe Hamas. One said I had "bought into" Hamas propaganda. Another that I should have dealt with Hamas' claims: "What's missing speaks volumes about your one-sidedness."
I do not believe anyone's "propaganda." We seek to verify all claims, from whatever source. One of the main claims in Gaza at the moment is the serious situation for the population. Having reported from Gaza many times over the years, I know how crowded parts of it are and how dependent the people are on food aid from the UN. This means they have no other source of supply but equally, if the system is working, they should be getting enough to get by on. The problem is that foreign correspondents cannot get in to establish the exact situation for themselves.