Israeli military forces use a "knock on roof" warning system in Gaza, to alert some residents when an airstrike is imminent.
Footage posted on YouTube by the Gaza-based Watania news agency apparently shows the controversial technique in action, with a small missile hitting the roof of what appears to be a residential building in the region. This is a "roof knock" warning.
Just over one minute later a rocket strike is blasted into the entire building, which the agency said was home to a man called Samir Nofal and his family.
In this instance the Israeli military had also provided a 15-minute phone warning ahead of the strikes and the Nofal family were able to warn neighbours and evacuate the building safely before the rockets hit.
It's been an emotionally exhausting day in Israel and Gaza as hopes for peace were raised then dashed then raised then dashed again.
In the court of international opinion, this is how Israel wins a battle and still manages to lose the war.
Until the Israelis and the Palestinians find a way of resolving the underlining conflict this will not be more than a pause.