Israel has invaded Lebanon. Here’s what could come next.

Israel has begun a military invasion of Lebanon it said would be “limited,” following days of bombing campaigns near and within the capital, Beirut.

The Israeli military said that it had moved one army division, typically numbering around 10,000 troops, to the Lebanese border and told Lebanese civilians in about two dozen villages in the area to move north.

That invasion marks a dangerous new phase in the long conflict between Israel and Hezbollah, an Iranian-backed Islamist militant organization and Lebanese political party that has fought Israel since its founding decades ago. Israel has recently escalated its attacks on Hezbollah, assassinating the group’s reclusive leader, Hassan Nasrallah, in a bombing in a Beirut suburb on Friday after reportedly launching a series of attacks on thousands of mobile devices used by members of Hezbollah throughout Lebanon.

Israel’s latest operations have been costly: More than 1,000 Lebanese have been killed, 6,000 wounded, and as many as a million displaced in recent weeks, according to Lebanese government officials. Hezbollah’s recent attacks on Israel — largely missile strikes — have meanwhile left at least eight people wounded in the last week.

Although the two sides have fought on and off over the decades, Hezbollah has been engaged in more intense fighting with Israel since the October 7 attacks on Israel by Hamas last year. Hezbollah has vowed to continue its missile strikes into Israeli territory until Israel agrees to a ceasefire in Gaza, where at least 40,000 Palestinians have been killed. Israel has shown no sign it is contemplating ending its operations, either. The country’s leaders have said they want to completely eradicate Hamas, and Israel’s defense minister said Monday that the “next stage in the war against Hezbollah will begin soon.”

Key allies also seem unable to end the fighting. The United States reportedly had a Hezbollah-Israel peace plan that it has now abandoned. While the US has publicly told Israel it should try to deescalate the situation, the US reportedly privately offered Israel support for its Hezbollah strategy.

Meanwhile, Iranian officials have responded to Israel’s recent attacks with a ballistic missile strike on Tuesday. Iran’s mission to the UN suggested the country did not have further attacks in store, writing on X that the country’s “response … has been duly carried out,” though it added the threat: “Should the Zionist regime dare to respond or commit further acts of malevolence, a subsequent and crushing response will ensue.”

Here is what we do know so far about what has happened, and what’s likely to come next.

The animosity between Hezbollah and Israel is decades old; in fact, Hezbollah formed in 1982 in southern Lebanon as a response to Israel’s disastrous invasion, which killed tens of thousands of Lebanese, and subsequent decades-long occupation of that area. Hezbollah waged guerilla warfare against Israeli troops for decades, and Israel finally left in 2000 following years of brutal fighting and a UN resolution requiring it to do so.

The two sides settled into a conflict that simmered until 2006. After Hezbollah killed eight Israeli soldiers and captured two others, Israel responded with a counterattack that led to a short, bloody war in which more than 1,000 Lebanese and 160 Israelis were killed. A UN-brokered ceasefire ended that conflict, but fighting continued for years — and it intensified again in the wake of Hamas’s October 7 attack.

Hezbollah is allied with Hamas, and, starting on October 8, 2023, began firing major salvos into northern Israel, eventually displacing around 60,000 residents there.

Initially, with Israel focused on uprooting Hamas in Gaza, fighting along its northern border with Lebanon was limited to tit-for-tat strikes. But starting in September, Israel escalated the fighting significantly, first by attacking Hezbollah members and leadership with exploding electronics, then bombing Hezbollah’s stronghold in southern Lebanon and the outskirts of Beirut.

Ever since the October 7 attack, observers have warned about the possibility that Israel’s war with Gaza might spread to encompass Hezbollah and, perhaps, the entire region.

It’s not clear if that’s what’s happening now or what a full-scale war between Israel and Hezbollah might look like. Despite Hezbollah’s previous ability to stand up to Israeli firepower, it’s also not clear how it will fare with its communication networks disrupted by the recent pager and walkie-talkie attacks — which Israel has not claimed but is widely assumed to be behind. What’s more, a significant number of mid-level and senior Hezbollah leaders were killed in that attack and subsequent bombings.

Hezbollah is considered the most widely armed and powerful militia group in the Middle East. It boasts a vast weapons arsenal, including as many as 120,000 missiles, and has deployed it with increasing success inside Israel’s borders since the war in Gaza began. Israel claims to have destroyed thousands of the group’s rockets and shells, and Natan Sachs, director of the Middle East policy program at the Brookings Institution, says Israel may have destroyed some of Hezbollah’s precision munitions.

Still, Hezbollah has demonstrated advanced military tactics such as using drones to fire missiles at key Israeli targets and effective intelligence capabilities including digital espionage. And recent Israeli attacks on Lebanese mobile devices and the assassination of Nasrallah haven’t completely wiped out that capacity.

“There was kind of this gleefulness about Hezbollah being completely disabled and destroyed now because all the leadership’s gone,” said Phillip Smyth, an independent analyst focusing on the Middle East and terrorism. “That’s not how it works.”

But the success of recent Israeli attacks has called into question the extent of Hezbollah’s capabilities — and reportedly shaken Iranian leadership. In that sense, Hezbollah may have limited options going forward, even though it had previously pledged not to relent until a ceasefire in Gaza is reached.

“Hezbollah turns out to be less capable, militarily, than I expected,” Thanassis Cambanis, a senior fellow and director of the think tank Century International, said.

Cambanis and other experts believed that Hezbollah had the technology to effectively strike military targets in Israel, as well as civilian infrastructure in Haifa and even Tel Aviv, a major population center. But if it was willing and able, it seems it would have done so by now.

“It turns out that Hezbollah wasn’t willing to use its most powerful military options, or that it couldn’t because Israel was able to infiltrate or neutralize Hezbollah capabilities,” Cambanis said.

The group’s second-in-command, Naim Qassem, sought to dispel doubts about Hezbollah’s capabilities in a speech on Monday, though he also seemed to suggest Hezbollah is currently on the defensive.

“Israel was not able to reach our military capabilities, and what its media says about hitting most of the medium and long-range capabilities is a dream they have not achieved and will never achieve,” Qassem said. “We will face any possibility and we are ready if the Israelis decide to enter by land and the resistance forces are ready for a ground engagement.”

He added that an announcement will be made in the coming days about Nasrallah’s successor, who Smyth said will most likely be Hashem Safieddine, Nasrallah’s handpicked heir and cousin. Safieddine currently oversees Hezbollah’s political affairs and sits on the council managing the group’s military operations.

Tuesday’s missile barrage is Iran’s most escalatory move since April, when the regime sent around 300 missiles and rockets toward Israel, nearly all of which were intercepted by US and regional partner forces, as well as Israel’s own air defenses.

For the most part, Iran asserts its regional power and carries out foreign policy goals — primarily, antagonizing Israel — by funding and providing resources to a network of militia groups. Those include Hamas, Yemen’s Houthi rebels, Shia militia groups in Iraq and Syria, and, of course, Hezbollah.

“Iran’s relationship with Hezbollah is really like two NATO allies,” Ali Vaez, director of the Iran project at the International Crisis Group, told Vox last October.

However, while NATO allies pledge to defend one another from attacks, Iran has been reluctant to be actively involved in a war against Israel; a drone attack on Israeli territory in April, following the assassination of an Iranian military leader in an Iranian diplomatic building in Damascus, Syria, was obviously telegraphed and minimally destructive. And the July assassination of Ismail Haniyeh, the former Hamas leader, while he was in Tehran prompted no obvious retaliation.

That’s not to say that Iran has no appetite for conflict: “The appetite for them was quite high, to be perfectly frank,” Smyth said. “They just thought that they could micromanage this so that it wouldn’t get to this point. And the Israelis clearly called their bluff.”

Now, it seems, Iran has offered a show of force — but there are limits to how far the country will go.

“Escalation could come, but [the Iranians] need to thread a needle,” Sachs said. That involves trying to show solidarity with Hezbollah and that Iran is capable of attack, without getting into an extended war with both Israel and the US.

Israel’s plan for its “limited” ground invasion involves rooting out Hezbollah along Lebanon’s southern border with Israel to neutralize the threat to Israeli communities nearby, the Washington Post reported. So far, the Israeli military said it has conducted “limited, localized and targeted raids” along the border.

But there’s a fear that Israel’s narrow mission could balloon into something bigger — much as it already has in Gaza, where Israel’s stated operational objective of eliminating Hamas has given way to widespread destruction of civilian life. If the conflict with Hezbollah does grow, that would likely spur fierce Lebanese resistance.

“An invasion of Lebanon will mobilize Lebanese as a national issue to resist, including the many Lebanese who don’t support Israel but also oppose another Israeli invasion and occupation,” Cambanis said. “Perhaps in the short term Israel can achieve some of its aims by pursuing the logic of total war, but it will only make Israel and the entire Middle East less safe.”

The Lebanese government — or what passes for it, since an unelected caretaker government has been in place since 2022 — has clearly demonstrated that the country is not interested in yet another war with Israel. Caretaker Prime Minister Najib Mikati announced Monday that his government is prepared to implement UN Security Council Resolution 1701, which ended the 2006 war. That resolution would deploy the Lebanese army to the country’s south to crack down on Hezbollah and require Israel to pull out of southern Lebanon. Now that Israel has entered Lebanon, it’s unclear whether Mikati will trigger the resolution.

The conflict has already taken a significant toll on Lebanese civilians and it could only get worse from here. In anticipation, Lebanon and the United Nations petitioned for $426 million in humanitarian aid on Tuesday to help those affected in the next three months.

Lebanon has already struggled under decades of war and government dysfunction, as well as an influx of Syrian refugees that have stretched already-limited state capacity. Now, Israel’s bombing attacks and invasion have displaced around 1 million Lebanese from the south of the country, according to Mikati, and the Lebanese government says at least 1,000 people have been killed in the past two weeks.

There seems to be no end in sight for the widening conflict, for several reasons: US unwillingness to restrain Israel by restricting weapons shipments; Hezbollah’s stated position that they will not stop attacks on Israel until a ceasefire with Gaza is reached; and the repeated breakdown of Gaza ceasefire talks.

The US and France did attempt to negotiate a 21-day ceasefire between Hezbollah and Israel last week, but “Israel (Netanyahu) has flat out rejected the US-French 21 day ceasefire proposal in Lebanon,” Joel Beinin, a professor of Middle East history at Stanford University, said. As Hezbollah also frames its attacks as support for Gaza, it most likely won’t agree to a ceasefire as long as Gaza is still under attack.

As for the US, there seems to be almost no effort to truly restrain Israel following the failed ceasefire attempt.

“The United States is just not driving events,” Michael Hanna, director of the US program at the International Crisis Group, said.

“We support Israel’s right to defend itself against Hezbollah and all Iranian backed terror groups. Of course, we know that mission creep can be a risk and we will keep discussing that with the Israelis. And ultimately, a diplomatic resolution is the only way to achieve lasting stability and security across the Israel-Lebanon border,” a spokesperson from the National Security Council told Vox in an email.

The US could, however, do more to deter escalation; Sen. Bernie Sanders (I-VT) has introduced a resolution to block arms sales to Israel, on the premise that the arms transfers violate international law, although that is unlikely to pass in Congress.

Although Lebanon is the current site of the crisis, Israeli military operations are ongoing in Gaza, where as many as 186,000 people may have been killed in the past year of fighting, according to the Lancet, a medical journal. (Many media sources put that figure at 40,000, but an accurate count is difficult given that much of Gaza is destroyed and fighting is ongoing.) Medical infrastructure has been destroyed, and there are many reported instances of communicable disease and malnutrition.

“People are getting killed in Gaza daily, the humanitarian situation is dire,” Hanna said. “Life is disrupted and on hold — there are no schools, there’s no functioning society. There’s nothing.”

Israel appears to be emboldened by its victories, and Hezbollah appears reluctant to launch large-scale attacks on Israel. The US has maintained its support for Israel and is sending more troops to the region. Iran has issued some threats, but hasn’t yet been much of an active participant in the fighting. All that makes it impossible to say where the war goes from here. Cambanis, however, predicts the worst.

“There’s a dangerous and delusional march to war on Iran,” he said. “I would have liked to rely on the US government to restrain Israel, but it’s clear that the Biden administration supports Israel’s widening gyre of escalation.”