A major war has been underway for a decade in the Middle East though it infrequently makes headlines. Month after month, week after week, and night after night, the Israelis have operated across the region against the Islamic Republic of Iran in what the Israeli government calls “the-war-between-wars” (or “the-campaign-between-wars”).[1]

The genesis of this war is clear. Since the early 1980s, Tehran has financed, armed, and trained terrorist proxies to target Israel. This includes Hezbollah in Lebanon, Hamas and Palestinian Islamic Jihad in Gaza, and more recently, Shiite militias in Syria and Iraq. Historically, Israel has battled many of these proxies in short but painful border wars. Tehran never paid a price. The Islamist regime preferred this dynamic, and the Israelis never altered the rules of engagement.

But over the last decade, Jerusalem has flipped the script. With the Iranian regime pushing ever closer to a nuclear weapon, the stakes are higher. Concurrently, Tehran is arming its proxies with increasingly lethal and precise weapons while striving to deploy them closer to Israel’s borders in a strategy of encirclement. With no other options, the Israel Defense Forces (IDF) have aggressively struck Iranian and Iran-backed targets. What began as an ad-hoc series of operations has evolved into a full-fledged campaign.

The individual strikes of this campaign, often conducted without attribution, were initially designed to forestall regional conflagration. Eroding the capabilities of Iran and its proxies, Israeli officials reasoned, would prevent the axis from placing sufficient assets in advantageous locations to launch a coordinated assault. As Defense Minister Benny Gantz said, “Sometimes the use of force, and a demonstration of it, is able to prevent the need for a stronger use of force.”[2]

But forestalling conflict in perpetuity is not a sustainable strategy. As the Iranian nuclear program advances, and as Tehran’s proxies amass lethal weapons on Israel’s borders, this shadow war may ultimately escalate to a wider conflict that could enable Jerusalem to neutralize or even eliminate its most significant threats.

While there was never an official start to the “war-between-wars,” the first shot was arguably fired in 2010 with the Israeli deployment of the “Stuxnet” worm, a joint U.S.-Israeli cyber-weapon that set back Tehran’s nuclear program by perhaps two years.[3] That attack garnered spectacular headlines, but it was certainly not the last. Over the past decade, the Israelis have increasingly operated against Iran in cyber-space. In 2018, for example, Tehran blamed Jerusalem for a cyber-attack against Iranian critical infrastructure,[4] and two years later, Israel was suspected of cyber-attacks against two Iranian government agencies and the Iranian port of Shahid Rajaee.[5] These are just a few of the Israeli cyber-operations that have been made public. In October 2022, the Atomic Energy Organization of Iran reported an “illegal infiltration,” which was widely assumed to be connected to Israel.[6]

Of course, Tehran has also hit Israel in cyber-space. In 2018, Iranian hackers penetrated the cellphone of IDF chief of staff Gantz, now a prominent politician.[7] According to news reports, in 2019, Iranian hackers almost infiltrated Israel’s missile early warning system.[8] In late 2020, Iranian hackers stole data from at least forty Israeli companies and even accessed Israel’s water system.[9] In early 2021, Iranian hackers targeted Israeli medical researchers, government agencies, academia, and more.[10]

Some Israeli analysts have pointed to concerns stemming from the lack of norms and rules associated with cyber-warfare.[11] Whether this is a serious problem for Jerusalem remains to be seen. For now, Israel is dominating Iran in this arena.

There is a psychological component to this cyber-warfare as well. In July 2021, for example, hackers accessed the message boards of Tehran’s central railway station and welcomed passengers to call the office of the country’s supreme leader, Ayatollah Ali Khamenei. Though it was suggested that an Iranian opposition group was responsible,[12] the Israelis likely had a hand in this activity, demonstrating the ability to operate deep inside Iran.

Even more jarring to the regime was the 2018 operation in which Mossad exfiltrated hundreds of thousands of documents from a secret nuclear archive on the outskirts of Tehran, which influenced the ongoing nuclear negotiations between Iran and P5+1 world powers (the United States, Russia, China, France, and Britain, with Germany).[13] Pointing to prior advances in weaponization that the regime had previously and vigorously denied, the documents alerted the International Atomic Energy Agency to nuclear sites previously obscured by the regime and sent nuclear experts scrambling to assess mountains of new data about Tehran’s nuclear program.[14] Tehran has since intensified its internal security; paranoia has increased commensurately.

In November 2020, Iran’s top nuclear scientist, Mohsen Fakhrizadeh, was killed in his car by a remote-controlled weapon suspected to be the handiwork of Mossad.[15] Fakhrizadeh’s demise did not deplete Tehran of its institutional nuclear knowledge, but it undeniably delivered a significant blow to the program, which Fakhrizadeh had led since 1989. Indeed, he was the head of Iran’s Organization of Defensive Innovation and Research (the Persian acronym is SPND) and of a secret program called “Project Amad,” conducting research on Iranian nuclear weapons.[16]

The Fakhrizadeh assassination was not an isolated event. Mossad was likely behind at least six other attacks against Iranian nuclear scientists since 2007.[17] The untimely deaths of Ardeshir Hosseinpou (2007), Masoud Ali Muhammadi (2010), Majid Shahriari (2010), Fereydoun Abbasi Davani (2010), Daryoush Rezaei Nejad (2011), and Mustafa Ahmadi Roshan (2012) all appeared designed to stymie the nuclear program by robbing it of institutional knowledge and human resources.

Unrelated to the nuclear program, in 2020, the Israelis were behind the assassination of Abu Muhammad al-Masri, al-Qaeda’s second-in-command, who had enjoyed safe haven in Tehran.[18] Since the 9/11 attacks, analysts have debated the nature of the ties between Tehran and al-Qaeda. Some argue this has been an uneasy relationship with many al-Qaeda operatives living under house arrest. Others assert that the Islamist regime has enabled the group’s terrorist activity. The assassination of Masri, who was roaming freely in Iran, certainly gave the appearance of collusion between the two.[19]

Israel and Iran have also engaged in maritime battles. In March 2021, Jerusalem struck an Iranian oil vessel bound for Syria, and in April, hit an Iranian spy ship in the Red Sea and an Iranian fuel tanker off Syria’s coast. Then, in May, an explosion attributed to the Israelis occurred on another Iranian oil tanker again off Syria’s coast.[20] According to The Wall Street Journal, Jerusalem had been targeting scores of Iranian vessels since 2019.[21]

The Israelis were struck in response. In March 2021, Tehran was likely behind an attack on an Israeli freighter near the Persian Gulf, and later that month, an Israeli-owned ship was hit by a missile off the coast of Oman.[22] In April, an Israeli-owned vessel was attacked off the coast of the United Arab Emirates, and later that year, the Israeli-managed Mercer Street was struck by an Iranian drone in international waters, drawing condemnation from world powers.[23]

Amidst all of this, Syria emerged as the most intense battleground. Tehran has exploited the decade-long civil war to entrench itself militarily in the country and to deliver large quantities of advanced weaponry to the Hezbollah terrorist group in Lebanon. Jerusalem has endeavored to prevent this from happening.

While the Israelis’ targets vary, most attacks are aimed at Hezbollah-bound, precision-guided munitions, which Jerusalem claims are “game changing” as they significantly upgrade the group’s “statistical rockets” that lack precision. Their trajectory can be manipulated in mid-air, and they strike with pinpoint accuracy. Israel has destroyed most of them, but officials cede a “few hundred” of the munitions have arrived in Lebanon.[24]

For a decade, there have been unwritten rules of engagement between the Iranians and Israelis. Tehran has willingly absorbed heavy losses so long as some weapons get through. Another unspoken rule is that Lebanon, the destination of most of these weapons, has been off-limits to Israeli strikes. The result has been thousands of strikes in Syria.[25]

For the first five years, Jerusalem was rather furtive, claiming no responsibility for what it struck. Yet, news reports provided clear contours of the battlespace. They pointed, for example, to Israeli strikes against a biological research center, to repeated attacks on advanced weapons bound for Hezbollah, and the assassinations of Hezbollah commanders, and even the killing of Iranian officers.[26]

By 2017, the war had begun to emerge from the shadows. In April, the IDF intercepted Hezbollah drones that penetrated Israel from Syria, and two months later, ten projectiles were fired into Israel, prompting Israeli strikes across Syria.[27] In February 2018, after Tehran sent a drone into Israel from the Syrian T4 airbase, the IDF launched airstrikes against Iranian and Syrian targets in Syria, including air defenses. Two months later, the Israelis struck an Iranian airbase in Syria, killing seven Iranian soldiers, and in May, fifteen Iranian and irregular fighters were killed in an Israeli strike on an Islamic Revolutionary Guard Corps (IRGC) installation.[28] Not long after, Israel struck more than fifty Iranian targets in Syria as part of “Operation House of Cards,” and in June, the IDF hit an Iran-backed militia in Iraq, killing twenty and destroying military assets.[29]

In February 2019, Jerusalem began to refer openly to this unacknowledged war when then-prime minister Benjamin Netanyahu boasted of a strike against Syrian targets.[30] In March, Acting Foreign Minister Israel Katz confirmed Israeli strikes against Iranian assets in Aleppo, and in April, Netanyahu hinted that Israel was behind a strike against an Iranian weapons factory.[31] In May, the IDF claimed credit for targeting a Syrian anti-aircraft battery.[32]

In May 2020, one non-governmental organization in Syria reported on nearly forty airstrikes up to that point, resulting in the death of 225 Iranian and Assad regime soldiers.[33] In June 2020, the Israelis attacked a Syrian onion-processing facility and a cattle-feed plant that the Iranians had converted into weapons warehouses while another strike destroyed a weapons convoy headed for Hezbollah in Lebanon.[34] In September, the IDF once again hit the T4 airbase, and three months later, an Israeli airstrike killed a top IRGC commander.[35] The Israelis were operating with increasing audacity. Indeed, one could detect a sense of pride among IDF brass and operators in off-record conversations about the Israeli military successes in Syria.[36] In October 2022, IDF officials went so far as to assert that 90 percent of Iranian military infrastructure was destroyed in Syria.[37]

In 2020, the trajectory of the “war-between-wars” was thrown into doubt. For the prior four years, the period representing the bulk of the campaign, the Trump administration had backed Jerusalem’s efforts to erode Iranian activity on Israeli borders. After Trump’s departure, President Joe Biden’s policy was unknown. Those uncertainties were settled in January 2021 when the Israelis struck Iranian and Hezbollah forces in Syria.[38] Then in October, the Israelis hit Syrian bases in Homs, followed three months later by a strike on containers in Syria’s seaport of Latakia.[39] None of this elicited a White House response.

Satellite imagery from February 2022 revealed damage to a drone base in western Iran, apparently the work of Jerusalem in response to the attempted delivery the previous year of weapons to the West Bank and Gaza by drones. Four weeks later, Tehran launched missiles at a compound in Erbil, Iraq, that it said was used by Israel.[40]

In April, Israeli warplanes struck Syrian weapons depots and centers where missile and unmanned aerial vehicles are being developed. Another report later that month confirmed an Israeli strike against Iranian ammunition depots near Damascus while a similar strike on ammunition near Damascus was reported in May.[41] In August 2022, Israeli jets struck western and central Syria, killing three soldiers and wounding three others. The Israelis also hit Damascus and Aleppo later that month in an apparent attempt to prevent Iranian planes from delivering military equipment.[42]

If Washington was unhappy about this activity, it did not state so publicly, even as the Biden administration pursued a nuclear deal with Tehran.

The Russian invasion of Ukraine in February 2022 introduced a new wrinkle into the war-between-wars. Since 2015, owing to Moscow’s military intervention in the Syrian civil war, the Israeli Air Force (IAF) has been forced to depend on Russian cooperation to operate in the skies over Syria. This has required careful de-confliction as the Russians patrol Syria’s skies with fighter jets and advanced anti-aircraft systems.

To sustain its campaign, Jerusalem has had no choice but to engage with Putin and his lieutenants. Early on, the two sides reached a tacit understanding that “Russia won’t interfere with Israel’s airstrikes in Syria.”[43] But the exchanges have not been without tension. Israeli pilots must operate within range of Russia’s formidable S-400 anti-aircraft system. This has likely encumbered Israeli operations to one extent or another.[44]

After the Russian army was slowed by determined Ukrainian resistance in 2022, the Kremlin reportedly elected to redeploy forces and assets out of Syria to Ukraine.[45] What that means for Israel remains to be seen. There are multiple ways in which Moscow could retain its military presence in Syria.[46] However, should the Russians remove anti-aircraft systems from central and eastern Syria, this could yield new opportunities for the Israelis in the unacknowledged war. Conversely, should the cooperative ties between Moscow and Tehran deepen, Jerusalem may find it increasingly difficult to operate on its northern border.

Until now, the war-between-wars has been a somewhat limited strategy to combat future Iranian threats. Questions now linger about its long-term viability as a vehicle for broader strikes to address the immediate existential and strategic threats from Tehran and its proxies. Former officials note that the strategy may help contain the problem in Syria, and even beyond, but that Jerusalem has been deterred from handling the true threats: Hezbollah’s growing precision-guided munitions (PGMs) stockpile in Lebanon, the appearance of additional PGM production facilities in Lebanon, and the construction of additional Iranian covert nuclear facilities, or, indeed, the overall advancement of Tehran’s nuclear program.[47]

Such criticisms do not negate the impact of the daring and successful Israeli operations in the undeclared war over the course of a decade. But these dangers cannot be ignored. Jerusalem may thus soon find that it must test the unwritten rules of engagement with Tehran. It may need to conduct riskier, asymmetric operations, especially as Hezbollah amasses additional PGMs and Tehran approaches Jerusalem’s red lines on the nuclear front.

Until then, the war-between-wars cannot stop. In the words of IAF former commander Amikam Norkin, “It’s not 100% success. But without our activity, the situation here might be much more negative.”[48]