As Iran continues to provoke the United States and its allies—sabotaging oil tankers, shooting down an American drone—it’s important to remember another kind of threat the Islamic Republic has in its arsenal if unchecked: its ally Hizballah, and, specifically, the Lebanese militia’s special-operations cells, which could be sent to attack not only Israel but the United States itself. “Hizballah is clear that if it comes to an American war with Iran, it wants in on the fight,” writes the analyst Matthew Levitt.

[This] is where Hizballah’s external operations apparatus, the Islamic Jihad Organization (IJO) or Unit 910, comes into play. Over the past several years, Hizballah IJO activities have been on the rise. The uptick began in 2008 as a means of avenging the assassination of Hizballah arch-terrorist Imad Mughniyeh, and later continued as a factor in Iran’s shadow war with the West over Tehran’s nuclear program.

Hizballah’s last successful attack targeted Israeli tourists in Burgas, Bulgaria, in 2012. But a long list of other plots has since been foiled around the world in places as far afield as Bolivia, Cyprus, Peru, Thailand, and the United Kingdom. Hizballah pre-operational surveillance occurred in Canada, Panama, the U.S., and elsewhere.

A recent case involving a Hizballah operative named Ali Kourani, who was arrested by the FBI, illustrates how Iran might order such attacks:

During one of Kourani’s meetings with the FBI, an interviewing agent recalled, Kourani sat back in his chair, squared his shoulders and stated, “I am a member of 910, also known as Islamic Jihad or the Black Ops of Hizballah. The unit is Iranian-controlled.” Within Hizballah, the unit reports directly to Nasrallah, according to Kourani, but Iran oversees the unit’s operations.

Kourani went on to describe himself to the FBI as being part of a “sleeper cell,” and explained, “There would be certain scenarios that would require action or conduct by those who belonged to the cell.” Kourani said that in the event that the United States and Iran went to war, the U.S. sleeper cell would expect to be called upon to act. And if the United States were to take certain unnamed actions targeting Hizballah, [its chief Hassan] Nasrallah himself, or Iranian interests, Kourani added, “in those scenarios the sleeper cell would also be triggered into action.”

One only need to look at Argentina to see what this kind of threat is capable of.

On Tuesday, a Hizballah drone attack injured three people in northern Israel. The next day, another attack, targeting an IDF base, injured eighteen people, six of them seriously, in Arab al-Amshe, also in the north. This second attack involved the simultaneous use of drones carrying explosives and guided antitank missiles. In both cases, the defensive systems that performed so successfully last weekend failed to stop the drones and missiles. Ron Ben-Yishai has a straightforward explanation as to why: the Lebanon-backed terrorist group is getting better at evading Israel defenses. He explains the three basis systems used to pilot these unmanned aircraft, and their practical effects:

These systems allow drones to act similarly to fighter jets, using “dead zones”—areas not visible to radar or other optical detection—to approach targets. They fly low initially, then ascend just before crashing and detonating on the target. The terrain of southern Lebanon is particularly conducive to such attacks.

But this requires skills that the terror group has honed over months of fighting against Israel. The latest attacks involved a large drone capable of carrying over 50 kg (110 lbs.) of explosives. The terrorists have likely analyzed Israel’s alert and interception systems, recognizing that shooting down their drones requires early detection to allow sufficient time for launching interceptors.

The IDF tries to detect any incoming drones on its radar, as it had done prior to the war. Despite Hizballah’s learning curve, the IDF’s technological edge offers an advantage. However, the military must recognize that any measure it takes is quickly observed and analyzed, and even the most effective defenses can be incomplete. The terrain near the Lebanon-Israel border continues to pose a challenge, necessitating technological solutions and significant financial investment.