Spy Mountain, the moniker for Mt. Avital, rises high on the Biblical Golan Heights. Surveillance antennas are conspicuous atop a heavily fortified installation. It’s Israel’s forward observation post peering into Syria; it’s also now the place from which Israel monitors Iran and its allies on the other side of the border. Roughly a kilometre away, on the Syrian side, is Sleeping Elephant Hill, nicknamed for its shape. In 2012, Iran’s Revolutionary Guard and its Hezbollah allies set up a signals-intelligence post on the hill to monitor Israel. In 2015, they attempted to set up a more robust military presence nearby. An Israeli air strike took out their reconnaissance team, including the Revolutionary Guard general Mohammad Ali Allah-Dadi and Jihad Mughniyah, the Iranian-trained son of Imad Mughniyah, the assassinated first military commander of Hezbollah.

As it usually does, Iran temporarily stepped back, regrouped, and modified its tactics. In 2016, the Revolutionary Guard started shipping kits to convert short-range rockets into longer-range missiles, with precision guidance systems capable of hitting strategic targets in Israel, from an electricity grid to an airport or a desalination plant. “That’s what’s called a game-changer,” Uzi Rubin, the former head of Israel’s Missile Defense Organization, told me. “They converted a weapon of terror into a military weapon for war. They’d only need two hundred to stop Israel’s ability to wage its own war.”

By early 2018, the Revolutionary Guard had deployed at some forty military facilities in Syria, with their own headquarters, drone-control rooms, and training centers. At least a third of them were deployed to target Israel, not just to prop up the Syrian regime in its civil war, Israeli defense officials told me. Since early 2017, Israel has launched more than two hundred strikes against Iranian targets in Syria—the most recent in August—to contain the buildup.

On a sunny day last year, I looked across a peaceful plateau that surrounds Spy Mountain and Sleeping Elephant Hill. The area is green with farmland, apple and pear orchards, and vineyards for Golan wine. Most of the time, it’s deceptively quiet. The Iranians are not visible. They now come and go dressed in Syrian military uniforms, a decoy tactic since Russia brokered a deal, a year ago, to keep Iran’s personnel and weaponry eighty-five kilometres from the border, Israeli officials told me. They’ve also hired residents in the Golan to work for them, as part of a widening network of armed allies in Syria, not all of whom are Syrian. And their weapons transfers keep coming.

Tehran and Jerusalem may be a thousand miles apart, but Iran’s so-called axis of resistance—which, by some counts, totals more than a hundred Shiite militias, with widely diverse manpower and matériel—has become entrenched across the Middle East, right up to Israel’s borders with Syria and Lebanon. Iran’s network spans half a dozen countries and has so fundamentally altered the region’s strategic balance that no nation can take on Iran and its proxies without risking multiple military challenges, major loss of life, devastating damage to infrastructure, or instability rippling through other nations. That applies even to the United States, nuclear-armed Israel, or Saudi Arabia, which spent fifty-five billion dollars—or roughly five times—more on defense in 2017 than Iran did.

Iran is unlikely to win a conflict. But it could insure that others don’t win, either, at least not in the classic sense of a decisive victory. If Israel tried to destroy Iran’s ally in Lebanon, Hezbollah, “we would be able to destroy Beirut, but they would be able to destroy parts of Tel Aviv,” Eran Etzion, the former head of policy planning at the Israeli Foreign Ministry, told me.

The same general principle applies to other countries contemplating military action against Iran after the September 14th attack on two Saudi sites that process more than half of the kingdom’s oil production. The Trump Administration blamed Tehran. On Wednesday, Saudi Arabia’s Ministry of Defense displayed parts of the weapons used in the attacks by eighteen unmanned drones and seven cruise missiles. Iran “sponsored” them, it claimed.

En route to Saudi Arabia, Secretary of State Mike Pompeo told reporters that the attack was “an act of war.” In an interview with CNN on Thursday, the Iranian Foreign Minister, Mohammad Javad Zarif, shot back with a warning of “all-out war” with “a lot of casualties” if the United States or Saudi Arabia strikes Iran. “I am making a very serious statement that we don’t want to engage in a military confrontation,” he said. “But we won’t blink to defend our territory.”

Iran could respond to any strike on its territory by unleashing its allies elsewhere in the Middle East, as it did in the nineteen-eighties, when it aided proxies that bombed two U.S. embassies and the barracks of U.S. Marine peacekeepers in Lebanon. The attacks ended up forcing the Reagan Administration to withdraw its peacekeepers.

Iran’s oldest, most sophisticated, and best-armed proxy is Lebanon’s Hezbollah. Iraq has the largest collection of Iranian-backed militias—more than sixty. Some are decades old; others are new. Syria hosts a growing array of Iran-orchestrated warlords, gangs, and armed groups created during the chaos of its civil war. Iran also arms and trains Yemen’s Houthi rebels, who claimed the September 14th attack on Saudi oil installations, and Hamas, which rules Gaza, and Palestinian Islamic Jihad. Among the more recent Iranian-mobilized militias are the Fatemiyoun, from Afghanistan, and the Zainabiyoun, from Pakistan. “Iran wants hegemony in the region not by re-creating the Persian Empire that occupied all lands to Egypt but, this time, by building up a satellite force across the region,” Rubin told me. Last year, the U.S. National Defense Strategy, the first in a decade, concluded, “In the Middle East, Iran is competing with its neighbors, asserting an arc of influence and instability while vying for regional hegemony, using state-sponsored terrorist activities, a growing network of proxies, and its missile program to achieve its objectives.”

The Trump Administration’s “maximum pressure” campaign, aimed at squeezing Iran economically, and Israel’s air strikes on Iranian targets in Syria, Lebanon, and Iraq have had limited impact, according to a report by the Center for Strategic and International Affairs. “There has been an increase in the overall size and capability of foreign forces that are partnered with the Islamic Revolutionary Guards Corps,” Seth Jones, a former adviser to the commanding general of U.S. Special Operations Forces, wrote. “Iran’s economic woes have not contributed to declining activism in the region.”

What’s shifted in recent years is Iran’s ability to consolidate allies and proxies into a web or grid that can operate regionally. The Islamic Republic facilitates the movement of militias to bolster other allies. The Quds Force pulled Shiite militias from Lebanon, Iraq, Pakistan, and Afghanistan to fight in Syria. In 2014, it manipulated the transfer of militias from the Shiite-dominated region of southern Iraq to Sunni regions in the north, to fight ISIS. It has fostered offshoots of Hezbollah in Iraq, Syria, and the Gulf, albeit with mixed effectiveness. “What matters is that Iran can now connect the dots—from Lebanon to Syria to Iraq,” an Israeli defense official told me.

Iran’s allies in the axis of resistance have, in turn, entered politics, transforming armed movements into powerful players in governments that decide policy. They’re altering the political status quo across the Middle East, too. Hezbollah emerged from the underground in 1992 to run for parliament in Lebanon, the most Westernized Arab country. Today, it has seats in parliament and also cabinet posts, and the Christian President is its hand-picked ally. By 2003, Iran had deepened its presence in Iraq through a network of Shiite militias commanded by Iranian-trained operatives. By 2014, a proliferating array of militias—with tens of thousands of fighters—merged into the Popular Mobilization Forces (P.M.F.) to fight ISIS after the Iraqi Army collapsed. The Baghdad government put them on its payroll. In 2016, Parliament made the P.M.F. an independent arm of Iraq’s security forces. In 2018, militia leaders and politicos ran for parliament. They now constitute one of the strongest blocs and had a major role in selecting Iraq’s latest Prime Minister.