Almost a year after Israel launched its war against Hamas in the Gaza Strip in retaliation for the Iran-backed group’s Oct. 7 terrorist rampage, it announced the beginning of what the Israel Defense Forces said would be “limited, localized, and targeted ground raids” against Iran’s much larger, better-armed proxy group Hezbollah in Lebanon. The ground operations were announced after about two weeks of blistering airstrikes on Hezbollah strongholds in southern Lebanon and the southern suburbs of Lebanon’s capital, Beirut, which have killed more than 1,000 people and displaced about 1 million people from their homes, according to Lebanese officials.

The aerial assault — and unprecedented covert operations before it that saw thousands of pagers and walkie talkies held by Hezbollah militants blown up with embedded explosives — have largely decapitated the U.S.-designated terrorist organization. It’s longtime leader Hassan Nasrallah was killed in an airstrike on Sept. 27, and at least half a dozen other senior figures, and dozens of mid-level operatives, have also been killed. But even as Israel prepared to launch its ground operation, Hezbollah’s surviving deputy leader said the group was ready for war.

Below is a look at how the arch enemies came to be at war again for the first time since a roughly one-month conflict in 2006 that left more than 1,000 people dead in Lebanon and more than 150 in Israel, and what’s at stake this time amid fear that Iran and the U.S. could be drawn into the fighting.

What’s happening now along the Israel-Lebanon border?

The Israeli military said on the evening of Sept. 30 that “targeted raids” against Hezbollah in the border area of southern Lebanon were underway. There were no immediate reports from inside Lebanon of significant ground operations, but Israeli airstrikes continued the morning after the IDF announcement.

Soldiers from the IDF’s 98th Division, comprised of several commando units, prepped in the darkness to enter the mountainous terrain across the border, where explosions were heard throughout the night.

On the morning of Oct. 1, the IDF warned residents in more than two dozen southern Lebanese towns and villages to evacuate their homes and head north, away from the border.

“Hezbollah’s activities are forcing the IDF to act against it. The IDF does not want to harm you, and for your own safety you must evacuate your homes immediately,” the military said in message delivered via social media, in Arabic. “Anyone who is near Hezbollah members, installations and combat equipment is putting his life in danger. Any home used by Hezbollah for its military needs is expected to be targeted.”

“Save your lives and evacuate your homes immediately,” IDF spokesman Lieutenant Colonel Avichay Adraee said in the message. “We will let you know when it is safe to return home.”

While the extent of the looming incursion remained unclear, at an IDF staging area just south of the Lebanese border, it was apparent that Israeli forces were preparing, at least, for a significant assault.

Dozens of tanks, armored fighting vehicles and bulldozers were lined up, ready for orders. On the other side of the border, just a few miles away, tens of thousands of Hezbollah fighters — with a vast tunnel network, a reputation for guerrilla warfare and suicide bombings — were dug in, waiting to defend the territory they have controlled for decades.

The last war, in 2006, ended with a cease-fire, and a United Nations peacekeeping mission of around 10,000 troops has been deployed near the border in Lebanon, along the so-called Blue Line, ever since. That mission, the United Nations Interim Force in Lebanon, called Israel’s plans to launch cross-border ground operations a “dangerous development,” noting that its “peacekeepers remain in position.”

“Peacekeeper safety and security is paramount, and all actors are reminded of their obligation to respect it. Any crossing into Lebanon is in violation of Lebanese sovereignty and territorial integrity,” UNIFIL said in a statement. “We urge all actors to step back from such escalatory acts, which will only lead to more violence and more bloodshed.”

Why is Israel attacking Hezbollah in Lebanon?

Israeli officials have said the goal of the operations against Hezbollah is to enable roughly 60,000 people forced to flee their homes in the northern part of the country to return. They were driven away — under evacuation orders in many cases — by a hail of rocket, drone and missile fire launched by Hezbollah militants inside Lebanon. 

That onslaught, albeit largely ineffective thanks to Israel’s advanced missile defense systems, began the day after Israel started bombing Hamas targets in Gaza in the wake of the Oct. 7 terrorist attack. That massacre saw Hamas and allied terrorists kill some 1,200 people in southern Israel, and take 251 others as hostages back into Gaza, according to Israeli officials. 

Since then, Israel says Hezbollah has fired more than 8,000 weapons across Lebanon’s southern border. The vast majority of the projectiles are intercepted, but some do crash down, and a handful of people have been wounded in northern and central Israel by the attacks, including two men hurt by rockets that hit a bus and another vehicle on Oct. 1. The most lethal attack was a rocket that slammed into a soccer field in the Israeli-controlled Golan Heights in July, killing 12 young people. Hezbollah denied firing the rocket, but Israel and the U.S. blamed the group. 

Israeli Prime Minister Benjamin Netanyahu has vowed to force Hezbollah back from the Lebanon border far enough to stop the barrage of rocket fire, so the displaced residents of northern towns and villages can go back to their homes.

“The reality is that, prior to October 7th, there was always a vulnerability [from Hezbollah], but Israel always thought it had been tamed,” Sanam Vakil, director of the Middle East and North Africa Program at the global affairs think tank Chatham House, told CBS News in September. “What October 7th has done, I think for Israel and Israelis, is reawaken them from, you know, that mirage that they were safe and secure. So going back to October 6th without altering the balance of power on Israel’s borders and within Israel seems hard to do.”

“We all feel suffocated by the situation. We don’t breathe,” Sarit Zehavi, a researcher who worked for 15 years in Israeli military intelligence and lives in northern Israel, told CBS News before the ground operations began. “On October 8th, basically, the war started here, with Hezbollah.”

Speaking with CBS News again on Oct. 1, Zehavi said she hoped the overall Israeli military operation against Hezbollah “will succeed — that we will succeed in eliminating all the [Hezbollah] ground infrastructure in the area next to the border.” But she recognized that a military assault alone was unlikely to ensure peace for northern Israel in the longer term.

“To tell the truth, I hope it will end with some kind of diplomatic arrangement that will enable us to breathe many more years, because they [Hezbollah] will strive to recover… After what happened on October 7th, you can no longer see Hezbollah on the other side of the border. This is the threat we cannot live with anymore.”

The U.S. stance and the risks of a new Israel-Hezbollah war

For weeks, President Biden has called for a cease-fire as Israel and Hezbollah exchanged increasing fire over the southern Lebanon border. U.S. officials at the White House, State Department and Pentagon have all made clear the risks of an all-out war between the close American ally and Iran’s most powerful proxy force in the heart of the Middle East could spiral into a broad regional conflict.

Iran backs a number of groups across the region, including Hezbollah, Hamas and the Houthi rebels in Yemen. Tehran refers to these groups as a “resistance front” against Israel’s decades-long occupation of Palestinian territory, while Israel refers to it as an axis of evil with the ideological goal of wiping the Jewish state off the map.

Hezbollah’s calls its rocket and drone attacks on Israel a legitimate support and defense of Palestinians in Gaza and the Israeli-occupied West Bank, and the Houthis have claimed the same rational for their months-long targeting of commercial and military vessels in the Red Sea.

One of the biggest risks, from a U.S. security perspective, is that Iran’s proxy groups — including smaller militias based in Iraq and Syria — will target American forces in the region in retaliation for Washington’s support of Israel. They have done so already since Oct. 7, firing rockets or drones at U.S. bases and other installations more than 165 times. Most of the attacks cause little to no damage, but a January drone assault on a U.S. outpost in Jordan, claimed by an Iran-backed group in Iraq, killed three U.S. troops and wounded dozens.

Despite the risks and Washington’s calls for deescalation, however, Israel has appeared determined to seize the momentum, with Hezbollah on a back foot in the wake of the aerial bombardment. The message has been clear: The best way to deescalate the war, from Israel’s perspective, is to win it.

contributed to this report.