After living in several Middle Eastern countries over the last few years, former pilot and aviation engineer Mohammed al-Zawari returned to his native Tunisia in 2011. Last month, as he sat in his car, assassins shot al-Zawari point blank and then vanished. An investigation followed, and Tunisian media outlets reported subsequent arrests by the police, but attributed the killing to Israel’s famed external intelligence agency – the Mossad. Hamas leaders were quick to acknowledge al-Zawari was one of their own and vow retaliation against Israel. Why would Israel go to such great lengths to have this Tunisian killed? Though aspects of his background remain mysterious, multiple reports describe al-Zawari as one of the leaders in charge of Hamas’ unmanned aerial vehicle (UAV) program – as well as a contributor to Hizballah’s drone arsenal.

Analysts continue to debate possible futures of UAV terrorism among a variety of actors, and an emerging consensus suggests that violent non-state actors will increasingly seek to exploit drone technology for nefarious purposes. The threat is particularly acute from powerful militant organizations, particularly groups that control enough territory to build sophisticated drone programs and engage in quasi-conventional military operations. UAVs possessed by militant groups are especially threatening to Israel: Of all advanced UAV programs run by violent non-state organizations, most are situated on Israel’s borders. While Israel maintains conventional air superiority over its neighboring rivals, drones can improve the asymmetric capabilities of Israel’s primary adversaries, Hamas and Hizballah – posing a national security challenge. As a result, Israel must engage in periodic military operations and targeted killings in an effort to degrade the UAV capabilities of adversary militant organizations. Engaging in such preventive actions is in line with Israel’s broader “mowing the grass” strategy devoted to containing and deterring its adversaries. In light of this latest assassination, it is worth briefly reviewing the increasingly prominent role UAVs play for the primary militant groups threatening Israel.

For years, both Hizballah and Hamas invested considerable resources into developing their respective UAV programs. During the Summer 2014 war in Gaza, Israel’s Patriot missile defence system intercepted Hamas UAVs on two separate occasions. Hamas’ military wing claimed that the second UAV was launched with the intention of carrying out an attack deep in Israel. Another Hamas drone reportedly malfunctioned and crashed after attempting to infiltrate Israeli airspace. Even though Hamas UAVs were neutralized early, the terrorist group claimed that just challenging Israeli airspace represented a victory for them. Hamas might also be seeking to test the air defense systems of Israel as well as Egypt. Drones, therefore, serve a variety of functions beyond targeted strikes, to include signalling and reconnaissance. While Hamas suffered significant setbacks after Israel’s 2014 operation, it continues to divert extensive resources to enhance its military infrastructure – including its UAV program – at the expense of civilian reconstruction projects.

As the world’s most powerful militant organization, Hizballah maintains a fleet of UAVs equipped with surveillance and reconnaissance equipment, as well as munitions. During the 2006 Lebanon War, Hezbollah crashed a drone armed with explosives into an Israeli warship, heavily damaging the vessel. The group’s ability to enter Israeli airspace on multiple occasions shows that Israel’s top-tier air defense systems is perhaps not optimized to detect and engage small and low-tech aircraft. In 2012, for example, a Hezbollah drone infiltrated 35 miles into the Israeli Negev and reached Dimona – the site of Israel’s nuclear reactor. The Israeli military stated that it was possible the UAV transmitted images of the nuclear facility. Weeks later a prominent Iranian politician declared that Iran possessed sensitive pictures acquired by the UAV. With advanced drone capabilities, powerful militant organizations are therefore in a far better position to successfully extract intelligence on sensitive targets and facilitate highly complex missions.

Since Hizballah’s military intervention in the Syrian Civil War, the organization has successfully utilized UAVs for a variety of functions, particularly intelligence gathering and coordinating military operations. The group also constructed a drone launch pad in Lebanon’s Beeka Valley and invested in other UAV-related infrastructure. In September 2014, Hizballah allegedly used an armed drone to attack militants affiliated with al-Qaeda in Syria. Some analysts question whether the incident occurred. If true, however, this watershed event would mark the first reported militant use of a UAV to inflict fatalities. Since then, more reports are emerging of powerful militant groups using UAVs for attack purposes, including the Islamic State group’s use of suicide drones mounted with explosives and even chemical agents. Hizballah has also released footage that supposedly show its drones dropping cluster bombs on Syrian rebel positions. Despite prioritizing its efforts in Syria, Hizballah continues to invest significant resources towards a future military confrontation with Israel. The group remains Israel’s top military threat, boasting battle-hardened troops that are capable of launching multi-pronged offensives, incorporating attack drones.

Though Hizballah and Hamas maintain domestic drone production capabilities, both groups rely on external support for their more advanced UAVs. Iran’s export of drones and UAV technology to its proxies has been widely documented. The Islamic Republic is reportedly constructing a fleet of suicide drones for Hamas and Hizballah and providing assembly instructions intended to facilitate kamikaze style missions. State sponsors are often critical for terrorist group success, but on-the-ground experts – like recently assassinated al-Zawari – are crucial in sustaining UAV programs and training militants to utilize drones effectively.

It is no mystery why Israeli national security personnel view UAV developments by militant groups with great concern. The threat from militant UAVs will grow as drone technology becomes increasingly cheaper and more effective – especially in the hands of operatives emerging from a more technologically savvy generation. After all, the Islamic State’s first reported suicide drone attack apparently came from a modified commercial drone. Israeli efforts to inhibit advanced enemy weapons programs require multi-faceted interventions, including discriminate strikes targeting sophisticated arms depots and key operatives. Some of these measures include striking enemy drone storage facilities and taking out key drone experts. While targeted killing effectiveness continues to fuel debate, campaigns to eliminate influential operatives disrupt terrorist operations, enhance mistrust within an organization, and force key members to constantly worry about their safety. It’s harder to plan effectively when simultaneously looking over your shoulder. Most importantly, highly skilled and educated experts – like a pilot or aviation engineer – are difficult to replace. Though Mohammed al-Zawari appeared to roam freely in a distant North African country without fear for his life, last month’s assassination sends a strong signal to Israel’s adversaries regardless of where they reside.

Michael Shkolnik is a Ph.D. Candidate at Carleton University’s Norman Paterson School of International Affairs. He served as a senior adviser with the Strategic Foresight unit in Canada’s foreign ministry, focusing on futures of terrorism and international security trends. In the past, Michael worked with security-related research institutes in Ottawa, Washington D.C., and Israel. The views expressed here are strictly those of the author.

Image: Soman, CC