TEL AVIV — In the early hours of April 9, Israeli fighter jets bombed the Tiyas air force base in central Syria, killing at least seven military personnel.
Israel wasn’t targeting Syria’s chemical weapons program, as the US would do four days later in response to Syrian President Bashar al-Assad’s chemical attack on civilians in the Syrian town of Douma.
Israel was instead going after a very different enemy: Iran. And the dead troops weren’t Syrian; they were Iranian.
It was far from the first time Israel has hit Iran and its various allied groups in Syria. Iran has alarmed Israeli and American officials by steadily expanding its military presence across Israel’s northern border with Syria in recent years, and Israel has responded numerous times. Some senior US and Israeli officials also worry that Tehran might restart its nuclear program if the Trump administration pulls out of the Iran nuclear deal, which President Trump has threatened to do by a self-imposed May 12 deadline.
But this latest strike was the most direct and brazen yet. Tehran has threatened to retaliate, and Israel has made clear that it’s prepared to keep fighting.
The Iranian response — considered now not a question of if, but when — could take many forms, ranging from missiles launched from Iran, Lebanon, or Syria against Israeli cities to cross-border raids from Syria or Lebanon to terror attacks against Israeli or Jewish targets abroad.
Israel, for its part, has promised an even stronger response if this happens, threatening all of Iran’s soldiers in Syria and even the Assad regime itself.
The tough talk reflects Jerusalem’s insistence that it won’t allow Tehran to turn Syria into a forward operating base for it and its proxies to attack Israel.
All of which points to a frightening and little-understood new reality: What was previously a shadow conflict inside Syria between Israel and Iran is now threatening to explode into all-out war between the two bitter Middle East foes.
The Syrian civil war turned a relatively quiet border into a war zone
Israel and Syria have technically been in a state of war since Israel’s founding in 1948. But as hard as it is to imagine now, for more than three decades, Syria was Israel’s least worrisome border.
The Assad family ruled the country with an iron hand but largely abided by a de facto ceasefire with Israel, preferring that its terrorist allies do the direct fighting.
As one senior Israeli military officer told me late last year, “it was comfortable to have [the Assad family] in control … it was our quietest front.”
That all changed with the outbreak of the Syrian civil war in 2011.
In the initial stages of the fighting, Sunni rebels with close ties to Saudi Arabia and other Gulf countries dealt Assad a string of battlefield defeats, and there was a real prospect of the strongman resigning or being forced from power.
That was unacceptable to Iran, which views Syria as its closest Arab ally. So Tehran went all in to bail out Assad.
Iran initially sent money, arms, and other logistical support — and then, when that wasn’t enough, military advisers from the elite Islamic Revolutionary Guards Corps (IRGC) and Hezbollah, the Lebanese Shia militia that has long been funded, armed, and trained by Iran.
In the early years of the Syrian civil war, Israel largely kept to the sidelines. The exception was with regard to what Israel considered its two red lines: Iran sending newer and more advanced weapons to Hezbollah through Syria, and the establishment of a pro-Iranian terror network on the Syrian border with Israel along the Golan Heights.
This first phase of the Israel-Iran showdown in Syria was thus conducted largely in the shadows and followed a well-worn pattern: An explosion would take place someplace in Syria, with later reports confirming that the target was a weapons convoy, an arms depot, or senior Iranian or Hezbollah operatives.
Israel wouldn’t take credit for the strike, but everyone in the region, including Syrian and Iranian leaders, knew who was responsible.
“We act when we need to act, including here across the border, with dozens of strikes meant to prevent Hezbollah [from obtaining] game-changing weaponry,” Israeli Prime Minister Benjamin Netanyahu confirmed in April 2016 on a tour of the Golan Heights.
Last year, Israel’s outgoing Air Force chief said that Israel had carried out close to 100 airstrikes on weapons convoys bound for Hezbollah, a staggering number.
Israel’s second red line — preventing the establishment of a terrorist network on the Golan Heights frontier — was upheld by Jerusalem just as ruthlessly, if at times with slightly more nuance.
The Golan Heights is a strategic area of elevated land situated along Israel’s northern border with Syria. For decades it was part of Syria, allowing Arab forces to shell Israelis on the ground beneath them.
Israel conquered the region during the 1967 war and later annexed it in a move not recognized by the international community. Israel and Syria had in past years discussed land-for-peace deals that called for Israel to withdraw from the territory in exchange for a comprehensive agreement.
But the prospects for such a pact disappeared right around the time the Syrian state disintegrated and went up in flames. Iran and its proxies have viewed the ensuing chaos as an opportunity to open a new front from which to attack Israel, and sporadic mortar shelling and small-arms fire were a feature of the early years of the Syrian civil war.
There was also at least one anti-tank missile attack and an improvised explosive device (IED) ambush on the border fence in 2014, killing an Israeli civilian and seriously injuring several Israeli army personnel, respectively.
Israel responded to these attacks with force, allegedly launching a series of attacks throughout 2015 and 2016 that killed several top Hezbollah operatives and IRGC commanders, including a brigadier general.
Israel never acknowledged playing a role in any of the strikes; indeed, one Israeli security official once told me, with a smile, that “every time one of their guys gets killed, it helps” — as if their deaths were due to a random bolt of lightning and not precision-guided munitions.
But it hasn’t been all targeted airstrikes and mystery explosions. In June 2016, the Israel Defense Forces (IDF) launched what they called the “Good Neighbor” policy. This was a program to provide Syrians across the border with medical assistance, humanitarian aid, food, and basic infrastructure like fuel generators and water piping.
It had a moral component: helping provide injured Syrians arriving at the border with medical care, often at Israeli hospitals. But it also had a harder-edged goal: to win the “hearts and minds” of the local Syrian population and dissuade them from cooperating with Iran and its allies.
“If we weren’t doing this, someone else would be,” the IDF officer commanding the “Good Neighbor” initiative told me last year, alluding to the yellow-and-green flag of Hezbollah. “There’s no such thing as a vacuum in this region.”
By late 2017, more than 4,000 Syrians had received medical care in Israeli hospitals, with the IDF running several hundred missions across the border into Syria.
Israel also reportedly began arming and funding various anti-Assad rebel groups in southern Syria. That was done to help offset the huge and growing battlefield advantage Assad had, and as a hedge against Iran and Hezbollah in the area. (Israeli military officials consistently deny the reports they arm and fund rebels, claiming their aid is strictly nonlethal.)
Israel’s newest red line: the establishment of a permanent Iranian military presence in Syria
So long as the Syrian civil war ground on and took a toll on Iranian forces, Israel appeared to be willing to stick to its prior, limited red lines.
The turning point likely came in December 2016, when the Syrian city of Aleppo fell to the Assad regime and Iranian-backed forces. (Russian warplanes had also bombarded the city.)
Israeli intelligence officials told me at the time that they feared Assad and his backers were going to win the civil war and then at some point turn their sights south, to the Golan Heights and Israel.
“We will simply not allow for Shia consolidation and Iranian entrenchment in Syria, nor will we allow Syria to become a forward operating base against the State of Israel,” Israeli Defense Minister Avigdor Lieberman said last year.
Tehran didn’t appear to be hiding the fact that that was exactly what it intended to establish. In November 2017, reports emerged about the construction of an alleged Iranian compound at a Syrian military base south of Damascus. Israeli jets bombed the site weeks later.
It does look like Iran has longer-term designs on Syria. At the height of the fighting, several thousand IRGC personnel, 8,000 Hezbollah fighters, and 30,000 other Shia militiamen from places like Iraq, Afghanistan, and Pakistan were committed to the fray.
After pouring billions of dollars into its Syrian project, buttressing the Assad regime and bankrolling Hezbollah and other Shia militias — and losing 1,000 of its own soldiers —Iran was not about to simply pack up and go home.
It was time to cash in on its hard-fought victory. Iranian companies have signed contracts to enter the Syrian market for everything from telecommunications to phosphates, agriculture, and academia.
More ominously (at least for Israel), Iran has raised the idea of establishing a naval outpost on Syria’s Mediterranean coast as well as permanent deployments at various Syrian airfields — primarily as bases for the IRGC’s drone, missile, and air defense units.
Israeli intelligence recently leaked five such locations to the press, signaling that it knew what Iran was doing and tacitly acknowledging that its third red line had been severely violated.
As Yossi Kuperwasser, a retired senior Israeli military intelligence officer, recently told me, “It’s true that Israel was more successful in preventing the delivery of weapons to Hezbollah and Iran from building an infrastructure for terrorism on the border than it was preventing Iran from building the basic infrastructure in Syria.”
An IRGC drone that crossed into Israel last February took off from one of those airbases, Tiyas (also called T-4); the IDF later claimed that the drone had been armed. An Israeli attack helicopter shot the drone down, and Israeli jets attacked its control caravan at the Tiyas airbase.
In the ensuing bombing raid, Syrian anti-aircraft missiles managed to down one of the Israeli F-16s (it crashed inside Israel, with the two pilots ejecting safely). It marked the first time since the early 1980s that an Israeli fighter jet had been shot down.
It also marked a major escalation in the Israeli-Iranian conflict — and a real step toward open conflict.
“This is the first time we saw Iran do something against Israel — not by proxy,” an Israeli military source told the New York Times. “This opened a new period.”
The Tiyas airbase was back in the news in early April when Israeli jets bombed it again, setting off the current crisis. Seven IRGC officers, including the colonel responsible for its drone program, were reported killed. Subsequent reports claimed that an additional target was an advanced anti-aircraft system that had just arrived from Iran.
The shadow war has now become a direct conflict between Iran and Israel
“Israel will get the necessary response sooner or later,” an Iranian foreign ministry spokesperson promised on April 16, adding that “the days of hit and run are over.”
Hezbollah chief Hassan Nasrallah went further, saying on April 13, “the Israelis need to know that they are in a face to face confrontation with Iran.”
Israel, for its part, shows no inclination of backing down. As one former IDF spokesperson told Israel’s Army Radio in mid-April, “We’re in open warfare with the IRGC in an ongoing campaign.”
Netanyahu, among many other Israeli officials, has threatened not only Iran’s military forces in Syria but also the Assad regime itself if the situation spirals out of control.
“The fighters of the IDF and security services are prepared for any development,” the Israeli premier said on the occasion of Israel’s 70th independence celebration on April 20. “We will not be deterred by the cost and we will exact a price from those who week our lives.”
The truly ominous problem is that each side has laid out positions that leave them little strategic wiggle room.
“I’m not saying no Iranians in Syria. They can have an Iranian embassy in Damascus,” Yaakov Nagel, a former national security adviser to Netanyahu, told me in mid-April. “[But] no military forces in Syria. Israel will not tolerate it.”
Iran, though, is unlikely to simply surrender its hard-won gains in Syria, and it has continued to issue bombastic threats of its own. “If Israel gives us an excuse — Tel Aviv and Haifa will be destroyed,” Ali Shirazi, an aide to the Iranian supreme leader, declared around the same time.
All of which means one very scary thing: The war between Israel and Iran in Syria that began seven years ago has now decidedly moved out of the shadows, hurtling toward its third — and potentially most destructive — phase.
The entire Middle East is perched on a knife’s edge.
Neri Zilber is a journalist based in Tel Aviv and an adjunct fellow of the Washington Institute for Near East Policy. Find him on Twitter @NeriZilber.
Correction: The original version of this article included a map that mistakenly labeled Saudi Arabia as Iraq. The map has been fixed.