Prior to striking a building in the Gaza Strip, the IDF warns its inhabitants using a procedure called "Knock on the roof," in which forces fire a small mortar at the target to indicate the imminent attack and signal those inside to flee before hitting it with full force.
A video documenting the mortar fired on the home of Hamas rocket unit head Ayman Siam at the Bureij refugee camp, and a short while afterwards the missile that almost destroyed the structure, shows how the "knock on the roof" procedure works.
Siam managed to escape the attack on Thursday with his life.
The video, posted on Palestinian news site Al-Watan, shows the mortar hit the house, causing a small cloud of smoke to rise.
The IDF usually gives the house's inhabitants longer, sometimes up to an hour, to flee the premises, but in the video, only 60 seconds pass from the warning mortar to the missile that strikes the house. This time, the blast is strong and when the smoke clears, the video shows the destruction of the structure.
In recent years, the IDF has sent out a warning ahead of a strike on a house in which innocent civilians might be found. These are buildings terrorists hide in or even operate from.
In accordance with international conventions, a message is sent to the residents of the house regarding the imminent strike using leaflets dropped from the air, phone calls, text messages and finally by launching a mortar that causes light damage to the roof of the house (but could wound or kill a person if the it hits him directly).
According to the procedure, it is only after the IDF makes sure residents have evacuated the premises that the missile that could destroy the house is launched.
During Operation Protective Edge, military Advocate General representatives are on hand to advise commanders on the legal repercussions of missions, as they did during Operation Pillar of Defense.