Home / Counter-Extremism / The use of civilian buildings for military purposes and the practice of “Roof Knocking”

The use of civilian buildings for military purposes and the practice of “Roof Knocking”

1 June, 2021

By Oliver Hegglin – Research Assistant

On the last day of Ramadan in 2021, 7 May, Israeli Police stormed the Al-Aqsa mosque in Jerusalem, where tens of thousands of Palestinians had gathered for prayer on the final Friday of Ramadan. The use of force, which ended up injuring over 170 Palestinians and several Israeli police officers, was justified with the claim of alleged rioting by the worshippers.

Violence between Israeli Police and Palestinians increased throughout Jerusalem in the days following, leading Hamas to threaten Israel with an ultimatum the following Monday, 10 May, should security forces not withdraw from the Al-Aqsa mosque compound. After expiration of the ultimatum, rocket attacks from the Gaza Strip into Israel began. Israel responded with air strikes against Hamas targets in the Gaza Strip. Increasing violence with thousands of rockets and hundreds of air strikes followed, ending with a cease-fire at 02:00 on 21 May.

As with previous conflicts in Gaza, this latest exchange of hostilities saw Palestinian militant groups use civilian buildings for military purposes, with subsequent Israeli attacks targeting these same civilian structures to eliminate a military threat. However, Israel employs a strategy known as “Roof Knocking”, designed to limit the number of civilian casualties caused by their airstrikes.

Misuse of civilian buildings

It is common knowledge that the militant Palestinian organization Hamas, an internationally recognized terrorist group operating in the West Bank and Gaza Strip, uses civilian buildings for military purposes. Residential buildings, mosques, hospitals, and schools have been reported to house Hamas installations and weapons storage areas. Other militant facilities are in the near vicinity from structures such as operational Covid-19 testing centers. It has also been assessed that upon the destruction of a misused structure, militants relocate to a nearby civilian structure, making more civilian buildings potential targets. This has led to the accusation that Hamas uses human shields, which they explain by pointing out the building density in the Gaza Strip. However, Hamas also allegedly attempts to win battles for “hearts and minds” by effectively forcing Israel to strike civilian targets, a tactic heavily criticized in the global media.

The Israeli Defense Force (IDF) is able to identify civilian buildings being used for potential military action, creating the need to find a way to reduce civilian casualties and collateral damage when attacking these locations. As a result, the practice of Roof Knocking was invented.

Roof Knocking

Introduced in the IDF’s 2008-2009 campaign in Gaza, Roof Knocking is the practice of warning inhabitants of a building of an imminent attack on their location. This is done by calling the occupants followed by a non-lethal rocket attack intended to shake the building in question. Nearby locations, such as schools, may also be notified of an impending attack in their vicinity. These phone numbers are acquired by the Shin Bet, Israel’s security agency, who creates lists of them. Civilians theoretically then have time to evacuate from the time of a Roof Knock to the subsequent strike.

Translated as “knock on the roof” from the original Hebrew hakesh bagag, this tactic has garnered controversy. It is alleged that civilians may not be granted enough time to evacuate while also being accused of justifying civilian casualties and being intended to spread terror. Israel claims Roof Knocking avoids the indiscriminate killing of civilians and is employed to follow the rules of war. Despite measures taken to mitigate civilian losses, by needing to retain the element of surprise, some innocent civilians would however, undoubtedly be killed.

The IDF’s International Law Department of the Military Advocate General has to approve every misused civilian target. The warnings are deemed to be critical for Israel as an ethical and moral obligation, while holding political and diplomatic significance. In practice, once a target has been approved, an Arabic-speaking intelligence officer would call the owner of the building, informing them of the incoming strike. An overhead drone would show the IDF how many people had evacuated and match that number with the believed number of residents. The green light to strike would then be given, destroying the building and the targeted military objective within.

The Fourth Gaza War

It is undisputed that a terrorist group indiscriminately firing rockets into Israel will force an Israeli reaction in the form of an air strike against the rocket launch site(s) and perhaps other high value targets previously identified, such as the home of a high-ranking Hamas leader.

The first major building in Gaza to be Roof Knocked in the May 2021 conflict was the Hanadi Tower in Gaza City, on May 11. This follows the first rockets fired at Israel from Gaza. Reports from approximately 18:45 stated that people in and near the tower had received calls from the IDF to evacuate, followed by the Knock itself at around 19:50. The destruction of the 13-story building was reported at around 20:10. This puts a 20-minute interval between the Knock and strike, with about an hour’s notice beforehand with the phone call. Images surfaced shortly after this time showing the complete destruction of the tower. The attack on the Hanadi Tower prompted the Al-Qassam Brigades to threaten Tel-Aviv, should Israel “proceed to dare and strike our civilian towers in Gaza”.

At approximately 20:55, more civilians in Gaza were being informed to evacuate buildings. Reports at about 22:15 stated that the Al-Jawhara Tower, which included “apartments and offices for journalists” was also hit. At about the same time, the IDF tweeted a message saying it was “striking Hamas weapons stores hidden inside civilian buildings in Gaza”, and that “although Hamas wants to put you in harm’s way, we urge you to stay away from Hamas’ weapons sites and get to safety”. Israeli Defense Minister Benny Gantz is to have said that “towers will continue to crumble” and that there were “a lot of targets in line”, at about 22:50.

By the next morning, multiple columns of smoke could be seen rising from Gaza, indicating multiple strikes occurred overnight. Another large building, the Al-Shorouk Tower, was hit with a Roof Knock from an IDF drone prior to 18:35. An initial strike destroyed part of the building at approximately 18:40 and a secondary strike the remainder at about 19:05. It is alleged that Hamas’ Al-Aqsa media offices were located inside this building. About one hour passed between the Roof Knock and initial strike. The destruction of civilian buildings quickly received international condemnation, prompting the IDF to share an infographic justifying why they attack multi-story buildings. In this, they state that only buildings classified as military targets are attacked and that “every feasible measure” is taken to enable the evacuation of civilians and mitigation of damage to property while pointing out Hamas’ alleged deliberate military use of civilian buildings.

By May 13, reports claimed that over 650 Hamas targets had been struck. On May 15, the Al-Jalaa tower, the building housing the Associated Press and Al-Jazeera offices in Gaza City, was also destroyed. Israel claimed the building was used by Hamas and is reported to have shared intelligence with the United States on these alleged operations. The explanation was reportedly “satisfactory”, making it a “perfectly legit target”. Israeli Prime Minister Benjamin Netanyahu is to have said that there were no deaths thanks to the measures taken. An article published by Al Jazeera itself reporting on the destruction of its office does say residents received warning calls and had about one hour to evacuate. By the evening hours of May 15 in Gaza, the Al-Andalus Tower was also Roof Knocked.

The Geneva Conventions and International Humanitarian Law

Additional Protocol I to the 1949 Geneva Conventions deals with the conducts of hostilities, part of which are regulated by the Customary International Humanitarian Law (IHL). Many articles, stemming from the 24 Principles of Distinction established by Customary IHL, are applicable to the Israeli-Palestinian conflict, including in the May 2021 hostilities. Of note are:

  • Article 48: Parties shall distinguish between civilian and military, and direct operations only against military objectives.
  • Article 51: The civilian population shall not be the object of attack. Indiscriminate attacks are prohibited.
  • Article 52: Civilian objects shall not be the object of attack. Military objectives are those which by their nature, location, purpose, or use make an effective contribution to military action and whose destruction offers a definite military advantage.
  • Article 57: Parties shall take all feasible precautions in the means and methods of attack to avoid and minimize loss of life. Effective warning shall be given of attacks which may affect the civilian population.
  • Article 58: Parties shall endeavor to remove the civilian population and objects from the vicinity of military objectives and avoid locating military objectives in/near densely populated areas.

War Crimes and Rules of War

Despite being a non-state actor, customary IHL norms also apply towards groups like Hamas. The use of civilian buildings for military purposes is therefore a clear violation of Article 58. By doing so, Hamas has effectively turned civilian buildings into military targets under Article 52. Furthermore, Hamas indiscriminately firing rockets into Israeli territory violates Articles 48, 51, 52, and 57.

The targeting and destruction of misused buildings by the IDF are arguably justifiable under IHL. With Roof Knocking and other measures designed to avoid and minimize the loss of life, Israel arguably fulfills the requirements of Article 57 when carrying out air strikes.

Despite mitigating efforts, civilians will continue to suffer because of militant and Israeli action and reaction. Hamas and other terrorist organizations are undoubtedly guilty of war crimes, however when it comes to Israel this is not so clear and perhaps not the case. What it may come down to is the principle of proportionality. Protocol I Article 51(5b) stipulates that an attack which may cause loss of life, or damage, which exceeds a military advantage, is indiscriminate and therefore forbidden.

The military advantage of buildings destroyed vary depending on the use, as, for example, rocket-launch sites and operations centers may be of different value. Though considering Hamas’ objective of the destruction of Israel, it can be safely assumed that any military location will ultimately serve this purpose. The destruction of locations providing a seemingly small military advantage in comparison with the potential loss of life must also be weighed with the long-term contribution to military action the continued existence of such locations will have, increasing their military value.

On 27 May, the UN’s Human Rights Council decided to open an investigation into human rights violations committed during the conflict. A permanent Commission of Inquiry would be set up to report on violations in Israel, Gaza, the West Bank and East Jerusalem. The UN’s human rights chief, Michelle Bachelet, stated that Israel’s actions may constitute war crimes, if they are “shown to be disproportionate”, and said that no evidence had been presented for alleged misuse of civilian buildings. While she also called on Hamas to refrain from indiscriminately firing rockets into Israeli territory, Prime Minister Netanyahu criticized the decision as another example of the body’s “blatant anti-Israel obsession”. Ultimately, the findings of this body are unlikely to have any effect in the region, as Israel will continue to use all means at its disposal to defend itself from attacks.

1,000 for one

In 2011, Israel swapped 1,027 Palestinian prisoners for one Israeli. This resonates with a simple statement repeated by the IDF and Israeli leaders time and time again – they will continue to defend the people of Israel. Which side began with hostilities and subsequent escalations is irrelevant – Israel will go to extreme lengths to defend its population. Understanding this means realizing Israel will continue to target misused civilian buildings to destroy the military contribution that building provides. While Roof Knocking and other measures designed to reduce civilian casualties will continue to be implemented, the loss of civilian lives when targeting such buildings will remain a terrible reality.

Image: the building used by foreign press offices is bombed in Gaza (Source: Osps7 (cropped from original) via CC BY-SA 4.0

About Oliver Hegglin

Oliver Hegglin is a geopolitical threat analyst in the private sector and has a master’s degree in international affairs from the Graduate Institute of International and Development Studies in Geneva and a dual bachelor’s degree in international studies and anthropology from Washington College. Between and during degrees he completed internships with diplomatic representations and the United Nations, and worked for a developmental NGO. Oliver is a Specialist Officer with Swiss Armed Forces International Command where he supports the training for peace support operations and has served abroad in Mali and Kosovo. He is a board member of the NGO Imholz Foundation. His research interests include peacekeeping, the Arctic and Swiss and global security issues.