The Wall Street Journal reported Friday that a year ago, Israel suffered its worst intelligence failure in its history when Hamas launched a surprise attack, killing 1,200 people, including 311 soldiers, and taking some 250 hostages. Today, a wave of strikes against Hezbollah has put Israel’s long-vaunted spy agencies and spies back in the spotlight.

“This shift reflects how Israel has invested its time and resources over the past two decades. Since fighting its last war with Hezbollah in Lebanon in 2006, Israel has been meticulously preparing for another major conflict with the militant group — and possibly with its backer, Iran,” the newspaper said.

Hamas, by contrast, was seen as a much less potent threat, the paper says. Even shortly before the October 7 incursion into the Gaza Strip, senior Israeli officials were dismissive of signs of an imminent attack. Last September, the Israeli military confidently described Gaza as in a state of “stable instability,” and “intelligence assessments concluded that Hamas had shifted its focus to stoking violence in the West Bank and wanted to reduce the risk of direct Israeli retaliation,” the paper says.

The pro-Israel newspaper quotes Carmit Valensi, a senior researcher at the Institute for National Security Studies in Tel Aviv and an expert on Lebanese militias, as saying: “Most of our focus was on preparing for a confrontation with Hezbollah. We somewhat neglected the southern arena and the developing situation with Hamas in Gaza.”

A series of Israeli attacks in Lebanon over the past two weeks has left Hezbollah stunned — shocked by Israel’s ability to penetrate the group and struggling to close the gaps. Thousands of Hezbollah radios exploded almost simultaneously on consecutive days last week, killing 37 and wounding about 3,000. Shortly afterward, an airstrike in Beirut killed a group of more than a dozen elite military commanders.

On Friday, Israel targeted what it described as Hezbollah's main headquarters in a Beirut suburb.

“But Hezbollah’s security remains tenuous. On Tuesday, another Israeli airstrike in southern Beirut killed Hezbollah’s top missile commander.”

The operations came nearly two months after Israel demonstrated its ability to penetrate Hezbollah by killing its top commander, Fouad Shukr, who had puzzled the United States for four decades. He was killed in an airstrike on his apartment on the top floors of a Beirut apartment building, where he had been summoned by phone shortly before.

An intensive campaign by Israel’s foreign spy agency, Mossad, and military intelligence units has destroyed Hezbollah’s leadership and degraded its weapons arsenal. The Israeli air force has followed up with a bombing campaign that has hit more than 2,000 targets this week.

Israel's military chief of staff said Wednesday the intensive efforts were in preparation for a ground invasion. The United States and its allies have been pressing both sides to halt the fighting, hoping to avoid another war or even a regional conflagration as fighting in Gaza drags on for its 12th month.

The Lebanese Health Ministry says more than 600 people have been killed in this week's air strikes on Lebanon, and about 2,000 injured, adding to the heavy toll on Gaza.

According to the newspaper, “Israel’s success against Hezbollah compared to its failure with regard to Hamas comes because the country’s security services are better at offense than defense, according to Avner Golov, a former director in Israel’s National Security Council who now works with MIND Israel, a national security consulting group.”

"The essence of the Israeli security doctrine is to take the war to the enemy. With Gaza, it was completely different. We were surprised, so it was a complete failure," Golov said.

Israel has watched Hezbollah’s buildup of its arsenal since the two sides signed a truce in 2006 after a month-long war. At the time, many in Israel’s security establishment were disappointed with the army’s performance in the war, which failed to inflict significant damage on Hezbollah, which had begun to rebuild its position in the south. As a result, the military sought to better understand Hezbollah and try to curtail Iranian military and financial support for the group, including through a campaign of airstrikes in Syria that became known as the “war between the wars.”

“In contrast, Prime Minister Benjamin Netanyahu has adopted a strategy of containing Hamas in Gaza in recent years, believing that the Palestinian group is focused on ruling Gaza and is not interested in a war with Israel. The two sides had fought a series of brief conflicts following Hamas’s takeover of the Gaza Strip in 2007, and the Israelis believed that the group’s leader in the territory, Yahya Sinwar, was more interested in improving the economic conditions of the Palestinian people,” the paper says.

The newspaper points out that "there were signs and evidence indicating that Hamas was planning the attack, including military exercises that indicated methods almost identical to those used by Hamas in its incursion into Israel on October 7."

But Israeli intelligence downplayed the exercises (which were being conducted by Hamas) as displays for domestic consumption, and the army felt very confident in the strength of the technologically advanced wall that the Israelis had built to separate Gaza from Israel.

“Gathering information from human sources that might have warned of an attack has become more difficult since Israel unilaterally withdrew from the Gaza Strip in 2005 and handed it over to Palestinian control,” said Uzi Shaya, a former Israeli intelligence official. “The ability to create human intelligence in Gaza, in a very dense and small area where everyone knows everyone, where a stranger appears immediately, makes life much more difficult,” Shaya said. “It has become easier to reach people in Lebanon or outside Lebanon who are connected to Hezbollah.”

But intelligence gains are limited, and ultimately Israel’s success against either group will be determined on the battlefield. “In the confines of the Gaza Strip, the IDF has defeated Hamas and destroyed the urban landscape. But it will face a different enemy in the hills of Lebanon.”

“There is a risk that Israel’s recent successes could make it overconfident,” said Valensi, a senior fellow at the Institute for National Security Studies. Invading Lebanon with troops could give Hezbollah the opportunity to demonstrate its military superiority on the ground, she said. “We’ve seen how challenging and difficult it is to take down a complex organization like Hamas. Hezbollah is a different story.”