Why did the Israeli advanced border security system fail to protect the country from an external attack?

Recently, Hamas launched surprise missile bombardments on Israel from Gaza, and Palestinian militants advanced into Israel by land, sea and air, in one of the most terrifying attacks Israel has known in the last years.

Some experts attribute Israel's failure to confront these attacks to two main factors: the element of surprise and the weakness of its protection system.

The element of surprise:
Although it is not the first time that Palestinian assaults on Israel have been launched or planned, recent attacks was unprecedented in terms of their strength, and because they were not expected at all by Israeli intelligence, as for they were described by international media as a "widespread intelligence and strategic failure." Indeed, more than 16 years have passed since an Israeli soldier was captured in an attack on Israeli territory: Gilad Shalit was captive for five years, before a deal was concluded in which more than a thousand Palestinian prisoners were released.

Israel has not witnessed this type of infiltration into military bases and towns since the 1948 war.

Insufficient protection:
It is clear that the entire defence structure failed to stop the attacks and provide the necessary protection measures for Israeli civilians.

But the Israeli army repeatedly evaded questions about whether the tragic events constituted an "intelligence failure." Army spokesman Richard Hecht told CNN that his country is focusing on the current fighting and protecting civilian lives. And he added: “We will talk about what happened from an intelligence standpoint later.”

Even the former Israeli prime minister Naftali Bennett declared on this subject: “In military history, there are always big surprises, such as Pearl Harbor and the Yom Kippur War. Ultimately, intelligence cannot go as far as it has.”

Since Israel withdrew from Gaza in 2005, it has spent billions of dollars for securing the border from potential attacks, and preventing armed Palestinian factions from to cross the border from the air or from underground using tunnels.
To stop the missile attacks, Israel used "Iron Dome", an effective missile defence system developed with US assistance.

Israel also spent hundreds of millions of dollars building a border system equipped with sensors and smart walls underground, which it was completed at the end of 2021.

Israel said that Hamas fired thousands of rockets at it, but it did not publish figures on the number of rockets that were intercepted. Officials did not comment on whether the smart border system had fulfilled its mission or not.

A former US State Department official on Middle East issues, told CNN that Israeli communities near Gaza “are clearly not adequately protected. And he added: “I don’t think the Israelis expected this to happen.”

It is noteworthy that Israel responded to the attacks by Palestinian factions by launching a military operation on the Gaza Strip, which has so far resulted in the killing of about 500 Palestinians and the injury of more than 2,000.