In some ways, Israel has never been more powerful. It boasts a close relationship with the Trump administration, a powerful and nuclear-armed military, and an air force capable of striking enemies hundreds of miles away. At the same time, it is a small country with limited infrastructure: It has one international airport, a handful of major power stations, and an electrical grid that Israeli experts have already warned is vulnerable to attack.

Iran and its Lebanese ally, Hezbollah, have obtained advanced missiles that are designed to exploit those weaknesses. For Israeli security officials, the nightmare scenario is that these weapons may become accurate enough to hit Israel’s civilian and military infrastructure, paralyzing daily life in the country. The threat they pose has already drawn Israel deeper into the Syrian conflict, and promises to fundamentally alter the next war with Hezbollah—a war that could come sooner than expected.

Since the beginning of the Syrian war, Israeli warplanes have struck Hezbollah arms convoys more than 100 times. A Syrian government offensive is sweeping through the southwest of the country, threatening to spark a further escalation. Syrian regime forces are approaching Israel, which has sent reinforcements to its side of the border to contain any spillover violence. Recently, Israel shot down two Syrian military drones that crossed into Israeli territory. While Iranian-backed fighters have played a low-profile role in the offensive, officials in Jerusalem remain worried that they could quietly move in once the Syrian government regains control.

The United States, Russia, and Israel are reportedly negotiating a diplomatic solution to the Syrian conflict that would establish a buffer zone free of Iran-backed forces near the Israeli border. Yet the threat from Hezbollah’s long-range missiles will remain. “Our concern is not Iran by the border. Our concern is Iran in Syria,” Michael Oren, a former Israeli ambassador to the United States and current deputy minister, told me. “Pulling Iranian forces away from the border doesn’t help you very much when [they] have a missile that can travel 200 kilometers.” Underscoring that point, on May 10, Iran and its allies fired 32 rockets at Israel from the Golan Heights; most landed short of the border or in unpopulated areas, and the rest were intercepted by Israel’s missile-defense system. The Hezbollah leader Hassan Nasrallah said the attacks marked a “new phase” in the conflict with Israel.

Since Hezbollah’s last war with Israel in 2006, it has expanded its rocket and missile stockpile. With Iran’s help, its arsenal is also now far more technologically advanced. Israel’s missile-defense systems can counter some threats, but would likely be overwhelmed by the sheer number of rockets and missiles that Hezbollah can now fire. “In the event of a war, the Israeli population will absorb blows that it has not experienced in decades,” Ofer Zalzberg, the International Crisis Group’s senior analyst for Israel and Palestine, told me.

In Lebanon, I met with Hajj Mohammed, a short, stocky veteran Hezbollah fighter. During the 2006 war, he fired constant barrages of short-range Katyusha rockets from south Lebanon into northern Israel. With Israeli jets prowling the skies, it was dangerous work. But Hezbollah was prepared: The Lebanese militia had concealed its launchers under concrete bunkers, rigging them to rise up using a hydraulic system, fire, and then disappear in the ground again. This system allowed Hezbollah to fire a steady stream of rockets for the duration of the war, forcing hundreds of thousands of Israelis to flee their homes.

While Hajj Mohammed was only too happy to relive the glories of 2006, his focus is fixed on the future. “Since 2006 until today, the game has changed entirely,” he said. “This time we have already chosen the targets, and we’ll make it rain missiles with pinpoint accuracy.”

Foreign-intelligence assessments appear to lend credence to Hajj Mohammed’s bravado. A senior U.S. counterterrorism official told me that Hezbollah’s arsenal includes at least 100,000 rockets and missiles, 10 times the number the group had in 2006. These weapons likely include the Iranian-made Fateh-110 missile, scud missiles, guided surface-to-air missiles that could target Israeli warplanes, and an increasingly sophisticated drone program, the official said. Israeli military officials, meanwhile, have warned that Hezbollah could fire 1,200 rockets a day in a future conflict—up from the roughly 100 rockets a day 12 years ago.

Hezbollah has long possessed rockets capable of striking deep within Israel, but they are more liable to land harmlessly in empty fields than to hit their target. In recent years, Iran has developed missiles with significantly improved accuracy—and Israel has focused on destroying them.

For Israeli officials, this new threat is embodied in the Fateh-110, a missile produced by Iran that retrofits long-range rockets with advanced guidance systems, allowing Hezbollah to make good on its threats. In the 2006 war, Hezbollah learned that unguided rockets could spark panic and mass evacuations among civilians, but were far less effective for striking military targets or critical infrastructure. While the Fateh-110 is not yet a precision missile, it is undoubtedly a more accurate weapon. Hajj Mohammed’s unguided rockets, if fired at Tel Aviv, would be just as likely to hit a point within 3.6 kilometers of his target as to land outside that zone. The Fateh-110, by comparison, whittles that margin of error down to roughly one kilometer.

Such missiles could still bring life in Tel Aviv and Jerusalem to a standstill and shut down Ben Gurion Airport. But they would not be accurate enough to destroy specific military targets. “I don’t think these newer capabilities that Iran is demonstrating will be militarily decisive,” said Michael Elleman, a senior fellow at the International Institute for Strategic Studies. “But it will complicate Israeli plans significantly.”

Iran’s missile capabilities, however, are improving every year. It could develop more advanced technology to regulate its missiles’ thrust, and outfit them with GPS systems. Perhaps more worrisome for the Israelis: Elleman said there is evidence that the Iranians are trying to miniaturize some of their guidance components, which could make some of Hezbollah’s smaller rockets more accurate as well. “It’s the direction in which this is all moving that is probably more worrying than their actual capacity today,” he said.

The Hezbollah leader Hassan Nasrallah has said that his group has transferred at least some Fateh-110s to Lebanon. Israeli defense officials have also expressed concern that the group maintains control of some of these missiles in the rugged, mountainous terrain of western Syria, allowing it to potentially strike Israel without igniting an all-out war in Lebanon. Israeli airstrikes against Hezbollah in Syria, meanwhile, could ignite the next war.

The damage done to Israel in another war will pale in comparison to the destruction wrought on Lebanon. Under a strategy outlined in 2008 that calls for the use of disproportionate force on any villages or neighborhoods in which Hezbollah operates, Lebanon would experience a level of destruction that “has not been seen since World War II,” one Israeli defense official was quoted in an International Crisis Group report as saying. “We will crush it and grind it to the ground.”

From a purely military perspective, such a strategy will eventually neutralize Hezbollah’s arsenal. Israeli warplanes will patrol the skies of Lebanon and Syria, working to destroy the launchers for the Fateh-110s and long-range unguided rockets. They will kill men like Hajj Mohammed and devastate Lebanon’s cities and villages to such a degree that international powers intervene to stop the war.

Oren said Israel will be forced to target civilian areas where Hezbollah has positioned its rockets, and advocates declaring war on the Lebanese government in a future conflict. But he also worried that Israel could be setting itself up for a Pyrrhic victory. The gory images from Israeli strikes would be transmitted across the world, he worries, inflicting a serious diplomatic blow on Israel. “The battle that begins in Lebanon doesn’t end in Lebanon. The battle in Lebanon, if Hezbollah wins, ends in The Hague. And the goal there is the systematic wearing away, erosion of our legitimacy. Our right to defend ourselves, and ultimately our right to exist,” he said. “And I’ve got to tell you, honestly, they’re winning this war.”