US intervention points to growing concerns over Israel’s air defences

As Israel’s conflict with Hezbollah and Iran has escalated, it has begun to show a degree of vulnerability. A Hezbollah drone evaded Israel’s much vaunted air defences on Sunday and struck a military canteen when it was busy with soldiers eating dinner. Four were killed and 58 wounded, seven seriously, at a location 40 miles south of the Lebanese border.

The drone that hit the canteen of the Golani base near Binyamina appears to have been part of a synchronised attack that allowed it to elude the country’s well organised air defences. Three drones flew from Lebanon over the Mediterranean, and though they were all initially spotted, and two shot down, the other was able to reach its target.

Why the third drone got away, eluding fighter jets, helicopters and the Iron Dome defence system, is a subject of urgent inquiry by the Israel Defense Forces (IDF). Hezbollah has been refining its attack strategy, and timing the drone attack with rockets helped complicate the picture for the defenders.

Related: Hezbollah drone attack kills four IDF soldiers as US prepares to send missile system to Israel

Drones may fly more slowly than missiles, but the Iranian-designed carbon-fibre models used by Hezbollah are hard to see and difficult for radar to pick up, a task made more complicated because they are flown deliberately low. Manoeuvrable, this drone, said to be Sayyad 107, resisted GPS guidance jamming, possibly because it used Russian or Chinese alternatives.

It is not the first time in recent days that a drone has got through. A retirement home in Herzliya was struck by a drone on Friday during the Yom Kippur holiday – one of two that crossed the border from Lebanon. The other was shot down successfully by a fighter jet, but the second struck the building a few miles north of Tel Aviv.

Israel’s air force said on Monday it intercepted more than 80% of incoming drones – 221 out of 1,200 that have been fired at the country during the war so far have got through. But an increase in the number of attacks and the growing sophistication of what remain relatively cheap to produce weapons will increase the risk of Israeli casualties as the fighting continues. However, the number of civilian and military casualties caused by Israeli attacks in Lebanon and Gaza remains far greater.

In the past 24 hours, 18 people were reported killed in strikes hitting the northern Lebanese town Aitou on Monday, while 22 people – including 15 children – were killed on Sunday in an attack on a school in central Gaza. But such is the asymmetry of the conflict that repeated successful strikes on Israel will raise questions about the completeness of the country’s air defences.

Though Iran’s large-scale ballistic missile attack on Israel at the beginning of the month was of a different order of magnitude, it too appears to have been more damaging than was initially acknowledged. It was judged at first by the number of casualties it caused – only one person, a Palestinian in the West Bank, was believed to have been killed. But the impact on buildings was greater than initially acknowledged.

Israel’s tax authority said on Sunday it had received 2,200 damage claims relating to civilian buildings following the 1 October attack, and a further 300 for vehicles and contents, taking the total damage estimate to 150m to 200m shekels (£31m to £41m). In Hod Hasharon, north-east of Tel Aviv, more than 1,000 homes were damaged, some impacted by a shockwave from a missile that smashed into an open area nearby.

Against such a backdrop, and with Israel expected to retaliate against Iran soon, it is not surprising that the US announced it would deploy one of its seven specialised Terminal High Altitude Area Defence (Thaad) systems in Israel, and a crew of nearly 100 US troops. Thaad is designed to defend against ballistic missiles, and will line up alongside Israel’s Arrow 2 and 3 and David’s Sling long and medium range defence systems.

Bringing Thaad to bear suggests the US believes that whatever Israel is planning to do will invite a fresh response from Iran, and that it could test existing air defences seriously. With Hezbollah also appearing to be causing problems of a different order for Israel’s air defences with its drone attacks, the overall situation is at risk of becoming more dangerous and fraught as the conflict turns into its second year.