Few sites in Israel are better protected than its main nuclear research facility and reactor, 8 miles from the town of Dimona in the southern Negev Desert.So when two Iranian ballistic missiles crashed into residential neighborhoods of Dimona and another nearby city, Arad, on Saturday night, evading the country’s vaunted air defence, even battle-hardened Israelis seemed rattled by the scenes of destruction.As alarming, perhaps, as the damage was military’s admission that it had tried to intercept the missiles, which struck about three hours apart. The failures raised questions about Israel’s multi-layered missile defence system and its ability to protect its citizens.And it renewed concerns that the military might be holding back on firing its most costly and sophisticated missiles, after reports that its stockpiles might have been drained in the 12-day war with Iran last year. Israeli military officials say they are investigating what went wrong but have been tight-lipped about the details.During a visit to the impact sites Sunday, PM Benjamin Netanyahu said it was a “miracle” that nobody had been killed. He urged Israelis to use the time provided by incoming missile alerts to head to bomb shelters. “Don’t be complacent,” he warned. He did not offer any explanation for the failed interceptions, nor did he mention the air defence system in which Israel and the US have invested heavily, over decades. While the military puts the interception rate of Iran’s ballistic missiles at more than 90%, officials and experts emphasise that the defences can never be 100% hermetic. “Dimona is protected with multi-layered defence systems – Israeli and American,” said Ran Kochav, a brigadier general in the reserves, “but nothing is perfect. There was an operational failure.” Brig Gen Effie Defrin, the military’s chief spokesperson, said Sunday. NYT