Israel has used a tactic called "roof knocking" for a while, but it became more widely known since Operation Protective Edge began last week. In an attempt to reduce civilian casualties, it involves hitting a target with a low-yield weapon as a warning, just moments before obliterating it with a much larger weapon.
Taken at face value, the technique appears to be clearly used for lowering the chances of civilians getting killed, or anyone getting killed for that matter, during Israeli air strikes on Hamas and Palestinian militant targets.
Yet some claim that it is a form of psychological warfare, and the time between when the "knock" is executed and full-scale bombardment is inadequate for people to vacate the premises being targeted.
Even if that was the case, Israel has been adamant that the targets in question have direct ties to attacks against its civilians, and usually have a connection with the storage, fabrication or the launching of unguided rockets. Some Hamas and other high-value military-related persons have had their homes targeted using this method as well.
Roof knocking is also usually paired with other tactics such as texting or calling those living or working inside the targeted building and near it, and telling them that a strike will be coming before the "roof knock" is executed.
Israel's Shin Bet intelligence service is known to easily penetrate Gaza's phone networks, and often the inhabitants are addressed by first name during warning calls to make it clear that they are serious. Leaflets have also been dropped around target areas warning of an impending attack and notices have been directly delivered to the areas targeted as well. So for some attacks, the warning starts with written warnings, then phone calls and/or texts, and the roof knock is the final warning to run just moments before an attack is executed.
As a response to Israeli airstrikes around Gaza, Hamas has promoted human-shield tactics, with civilians being deployed to the rooftops of key targets and to the homes of some of Hamas's leadership.
At any given time during outbreaks of violence between Israel and Hamas, the skies over the Gaza Strip can have multiple layers of intelligence surveillance and reconnaissance (ISR) aircraft, from Hermes, Eitan and Heron drones, to turboprop powered manned aircraft, not to mention fighters and attack helicopters, orbiting in it. Small FLIR equipped drones work with their heavier armed drone cousins as hunter-killer teams looking for rocket launch sites, while F-16 and F-15 fighter-bombers and AH-64 Apache attack helicopters can be called upon to strike larger and time-sensitive mobile or fixed strategic targets.
It is not precisely clear what weapon systems execute "roof knocking" itself, but there is a good chance that an unmanned aircraft drops a guided micro-munition that acts as a warning charge. Such a device probably has a fairly impotent air burst concussion type warhead, or if it is a heavier artillery shell or guided bomb, it may be totally non-explosive and filled with concrete. The strike immediately following the roof knocking event is usually delivered by either tactical fighter, attack helicopter, or possibly artillery depending on the target's qualities.
Amnesty International and other groups are urging the UN to investigate both Hamas and the Israeli Defense Forces for war crimes since this new round of hostilities broke out last week. Spurred by the killing of Israeli teenagers by Hamas militants, Israel launched strikes in Gaza, which in turn prompted Hamas to lob large salvos of rockets as far north as Tel Aviv, many of which were intercepted by Iron Dome at $50k per missile interceptors, of which two are usually launched at every Hamas rocket that is predicted to land in a deadly area.
In reality, Amnesty International's calls for war crimes investigations means nothing, aside from recognizing that business as usual continues unchecked in this volatile part of the world.
Meanwhile, the nauseating tit-for-tat cycle of violence continues to spiral along with no plausible end in sight.
Tyler Rogoway is a defense journalist and photographer that maintains the website Foxtrot Alpha for Jalopnik.com You can reach Tyler with story ideas or direct comments regarding this or any other defense topic via the email address Tyler@Jalopnik.com