Commenting on last week’s bombing—the fifth terrorist attack in Britain this year—Andrew McCarthy writes:

For many years, terrorists aspired to major operations—spectacular strikes that required know-how, discipline, and coordination. [Security officials] were able to say with confidence that if [they] focused on training—not just ideological fervor but whether a would-be militant had been to a jihadist camp—[they] would have a reasonably good handle on who posed a threat. This is why, for example, [the U.S.] amended immigration law after the 9/11 attacks to preclude from entry into the country any alien suspected of receiving jihadist training. . . . But . . . it doesn’t require any training to . . . plow a car into a crowd of people.

Terrorist organizations like Islamic State have encouraged [their supporters] to attack in-place—i.e., where they live in the West—rather than come to [fight in] Syria. We are thus seeing more of these ad-hoc strikes that require little or no expertise to pull off. In the 1990s, [American law-enforcement officials] used to be ironically relieved that the jihadists always wanted to go for the big bang; 9/11-type attacks are horrific, but they are extremely tough to pull off, and there are usually opportunities (as there were with 9/11) to disrupt them. That’s why they so rarely succeed. We worried that someday it would dawn on these monsters that there is a great deal of low-hanging fruit out there (virtually indefensible targets, like subways and crowded streets) that would be easy to attack, almost no preparation or coordination required.

Now, they’re going for the low-hanging fruit. In terms of what the wonks like to call the “threat mosaic,” we are now in straits more dangerous than ever. We have highly trained, competent jihadists who are capable of pulling off sophisticated strikes that could kill hundreds or thousands at once; and we have motivated would-be jihadists who have been encouraged to do the kind of crude attacks that are within their limited capabilities. The crude attacks, we are learning, are just as effective at stoking an atmosphere of intimidation as long as they happen with some regularity.

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.