While much of the world’s attention has focused in recent weeks on the escalating tensions between two of the Middle East’s geopolitical rivals — Saudi Arabia and Iran — a powerful clash of interests is unfolding between Iran and another regional heavyweight, Israel. The crux of the matter is Israel’s concern that as the Syrian conflict approaches its final stages, Iran will be able to enhance and cement its military presence in the country in a way that will inevitably threaten Israeli interests. Iran’s plans to set up permanent military bases and build weapons production plants in Syria are thus placing Israel and Iran on a dangerous collision course. Friction is already evident: On Dec. 2, Israeli fighter jets targeted a military compound south of Damascus, in which Iran planned to permanently station hundreds of troops. Two days later, another high-value target was bombed — this time a Syrian military facility connected to Iran’s efforts to produce precision-guided missiles in Lebanon and Syria.

This confrontation is likely to cause further friction along the Israeli-Syrian frontier. However, the clash now threatens the remarkable stability that has prevailed in Lebanon in recent years between Israel and Hizballah, Iran’s proxy ally. Indeed, while Israel, Iran, and Hizballah have clashed in Syria, they have managed to keep the Syrian and Lebanese arenas separate, in part because of a mutual desire to avoid another war in Lebanon. Recently, however, Israel, Hizballah, Syria, and Iran have engaged in belligerent rhetoric about a potential regional war. Against this increasingly volatile backdrop, continued stability between Israel and Lebanon will depend on the parties’ willingness and ability to insulate the Israel-Hizballah conflict from the wider events in the region. Specifically, Israel and Hizballah will need to separate the Syrian and Lebanese arenas by communicating to each other — through indirect back-channels, public statements, and their actual behavior — that what happens in Syria stays in Syria.

Deterrence and Stability on the Israel-Lebanon Border

Throughout the 1990s, Hizballah fought a guerrilla war against Israel’s occupation of southern Lebanon, which lasted until the latter’s unilateral pullout in 2000. Soon after, Hizballah resumed its military operations against Israel; in the following years, mutually understood tit-for-tat rules of the game gradually emerged. However, in July 2006, Hizballah abducted two IDF soldiers in a cross-border attack that blatantly violated these rules. The incident quickly spiraled into a costly 34-day war that neither side saw coming and both regretted.

In the 11 years since the Second Lebanon War, the border between Israel and Lebanon has seen a degree of stability unprecedented in half a century. UN patrols continue to jointly monitor the border regularly, and far from the limelight, senior Israeli and Lebanese officers continue to hold UN-mediated monthly meetings to preserve the quiet along the border. Last April, Lebanese Prime Minister Saad al-Hariri, while touring the border, even urged the United Nations “to secure, as soon as possible, a state of permanent ceasefire.” Recently, in another sign of stabilization, it was revealed that the two countries, although technically at war, have been allowing Christian Arabs from Israel to make monthly pilgrimages to Lebanon.

More importantly, with a few exceptions, Lebanon and Syria have remained separate arenas in the Israel-Hizballah conflict. Hizballah and Israel have since 2006 had a shared interest in preventing another war in Lebanon. But Syria’s descent into chaos, and the deployment of thousands of Hizballah fighters in Syria beginning in 2012, has opened up an arena in which Israel and Hizballah lacked common experience and accepted “rules of the game.” In Syria, Iran’s regional interests dominate Hezbollah’s calculations more than in Lebanon. Therefore, while Hezbollah is an integral part of Iran’s regional strategy, there is a partial divergence of interests when it comes to Lebanese and Syrian arenas.

This separation can also be explained by Hizballah’s ability to deter Israel from attacking Lebanon. Nowhere has this distinction been more evident than in the fact that while Israel has habitually targeted Hizballah-bound weapons shipments in Syria, it has been deterred from targeting the same shipments once they reached Lebanon. This achievement forced Hizballah to live with Israel’s air raids in Syria as part of the “acceptable” rules of the game and refrain from any meaningful attempt to extend its deterrence into the Syrian arena. Israel has made it clear that it would not allow Hizballah to establish a military presence along its border with Syria similar to the stronghold it has established in Lebanon.

Perhaps the most fascinating development in the conflict since the last all-out military encounter in 2006 has been conceptual, with the two parties coming to perceive and define their conflict as being governed by deterrence. Israel and Hizballah systematically and explicitly refer to deterrence as their strategy for avoiding another war. As Israeli Defense Minister Avigdor Lieberman has said, “our entire challenge as a military, and mine, too … is to prevent the next war. This you can achieve only by means of deterrence and resolve.” Deterrence, Lieberman added, is achieved when “nobody doubts your credibility.”

As I have shown in a recent study in International Security, Hizballah, too, has engaged in the calculated and purposeful pursuit of deterrence. Beyond the enhancement of its military capabilities, the organization has systematically invested in deterrence communication — carefully delivered threats designed to convince Israel that in any future war Hizballah would impose exorbitant costs on the country, namely by firing precision guided missiles on vital Israeli strategic assets. As Hizballah Secretary General Hasan Nasrallah stated last year in a message directed at Israel, “We have a clear equation: Do not attack Lebanon. Should you attack, any assault will be met with an appropriate retaliation.” In the words of its secretary general, Hizballah has engaged in a sustained effort to make Israel “constantly balance costs and benefits.

Volatility in Syria

However, in the Syrian sphere the situation is far more precarious, for two main reasons. First, Israel has not been deterred by Hezbollah or others from conducting air strikes in Syria. Israel is determined to prevent Hezbollah from acquiring weapons systems that could undercut its aerial superiority, which has outweighed Hezbollah’s motivation to risk a confrontation with Israel over the strikes — as long as they take place outside of Lebanon. The second reason is the inescapable clash between Israel’s vital security interests and the aspirations and interests of Hizballah’s patron, Iran, in the Syrian arena. This clash has been a long time coming — at least since the United States set out to “degrade and ultimately defeat” the Islamic State (ISIL) in Syria in 2014. When the United States formed the anti-ISIL coalition, a senior IDF commander pointed out, “the United States, Canada and France are on the same side as Hizballah, Iran, and Assad. That does not make sense.” From Israel’s vantage point, it was the Axis of Resistance — a regional Iran-led coalition made up of Syria, Iraq, and Hizballah — that stood to gain most from the defeat of ISIL in Syria. The way Israel sees it, three years on, this is precisely where things stand. Assad’s apparent victory seems to guarantee Tehran’s influence in the country as well as the contiguous land corridor from Iran to Lebanon.

According to Israeli reports, Iran plans to establish naval and air force bases in Syria, deploy thousands of troops, and build missile production facilities in Syria and Lebanon. For Israel, the nightmare scenario is that when the dust finally settles on the Syrian crisis, it will find itself in an unbearably vulnerable situation, effectively sharing a border with its archenemy Iran. In this scenario, an empowered Tehran could threaten Israel, directly or through proxies, from within Syria, while suffering no corresponding vulnerability to its own territory.

Iran may attempt to use Hizballah’s military might in Lebanon to counter Israel in Syria, thereby undermining the separation between the two spheres. Whether or not this will succeed will depend on how involved Hizballah becomes in Iran’s efforts in Syria. If Hizballah commanders start taking an active role in Syria, Israel could resort to force. In early 2015, Hizballah chose to retaliate for an Israeli attack on several of its activists in Syria with an attack along the Israeli-Lebanese border — an operation that claimed the lives of two IDF soldiers and could have sparked a much bigger conflagration. The more Hizballah becomes involved in Iran’s efforts to deter or punish Israel for its actions in Syria, the more likely are we to see instability along the Israeli-Lebanese border.

Fighting Words

The possibility that the Syrian conflict could become a wider regional confrontation is the context in which to understand Israel’s escalating rhetoric toward Iran, Syria, and Hizballah. In June, the IDF Intelligence chief asserted that “never has a military known more about its enemy than we do about Hizballah.” Israel’s Air Force commander followed suit, saying, “over the past 4-5 years, we have quadrupled our capabilities. What we were able to do in the Second Lebanon War in 34 days we now know how to do in 48-60 hours.” In September, the IDF Northern Command conducted a two-week military drill, its biggest in two decades, after which the Israeli defense minister declared, “The next confrontation, should it break out, will end in a clear and decisive victory.”

The precarious regional situation has also been punctuated by threats, counter-threats and military incidents along the Israeli-Syrian border. For instance, on Sept. 19, Israel shot down an Iranian-made, Hizballah-operated drone that violated the demilitarized zone between Israel and Syria. On Oct. 21, four rockets hit the Israeli side of the Golan Heights. On Nov. 11, Israel once again shot down a Syrian spy drone approaching the demilitarized zone. A week later, an IDF tank fired warning shots into Syria to deter Syria troops from encroaching on the demilitarized zone.

Israel has stepped up its diplomatic campaign as well. Importantly, its leaders held contacts with their Russian counterparts to stress that Israel is determined to prevent Iran from turning Syria into a frontline base against Israel — a message Prime Minister Benjamin Netanyahu and Lieberman have repeated since then. On Dec. 13, Israel’s Intelligence Minister Yisrael Katz told the Saudi news website Elaph that Israel “will act militarily” to stop Iran from building missile production plants in Lebanon. “For us it is … a red line.”

It was against this backdrop that Hizballah leader Hassan Nasrallah accused Israel of trying to “push the region towards a new war.” He claimed Israel lacks a sound assessment as to “what would be its geographical scope … who would take part in it, and who would join it,” a veiled reference to other members of the Axis of Resistance. Indirectly replying to Nasrallah, Lieberman said that while “our entire effort is to prevent the next war,” such a war would be conducted on “one theater, Syria and Lebanon together, Hizballah, the Assad regime and all of the Assad regime’s collaborators.”

For its part, a veteran Syrian presidential adviser backed Hizballah’s deterrent posture, saying that Damascus would not enable Israel to single out the group. The adviser explained that a “sense of joint fate” has become “more firmly rooted” among the “resistance front” made up of Iran, Iraq, Syria, and Hizballah. Syrian President Bashar al-Assad then took this a step forward: Asked what would be his country’s position if Israel attacked Hizballah, Assad replied that “the Syrian and Lebanese front against the Israeli enemy has become one.” Last month, the top adviser to Iran’s supreme leader described the alliance as a “resistance line” that “starts from Tehran and passes through Baghdad, Damascus and Beirut to reach Palestine.” Also over the past month, the commanders of three Iran-backed Iraqi militias have pledged to come to Hizballah’s assistance should it be attacked by Israel. In an unmistakable signal to Israel, one of the commanders, Qais al-Khazali, of the Asa’ib Ahl al-Haq, made his statement while touring the Lebanese-Israeli border in early December. These statements from Hizballah’s allies represent a purposeful and concerted effort to enhance the deterrence posture of the Axis of Resistance.

Preventing Spillover into Lebanon

The pressing regional challenge right now is the need to prevent the violent bargaining process between Israel and Iran in Syria from igniting the Israeli-Lebanese front. As a top IDF commander recently told me, while he does not see Israel and Hizballah going to war “in the next year, or even in the next two years,” the potential for war lies not in a tactical “miscalculation” but rather in Iran’s long-term advances in the Syrian arena.

From a deterrence standpoint, Israel and Hizballah may be wise to threaten each other with all-out war. But stability in the Lebanese arena depends on their willingness and ability not just to respect each other’s red lines, but also to insulate the conflict in the Israel-Lebanon sphere from the wider developments in Syria. After all, while Hizballah may be viewed as an integral part of the Axis of Resistance, the organization’s interests are not necessarily identical to those of Iran, Syria, or the Iraqi militias. Ultimately, Israel and Hizballah share a strong interest: to maintain deterrence and avoid another all-out war. The parties have a lot to work with: for a quarter of a century now, the Israel-Hizballah conflict has tacitly but effectively been rules-based. Both parties have gained considerable shared knowledge, and both continue to share an interest in avoiding another full-scale war.

Given the shifting center of gravity in the Syrian arena, Israel and Hizballah would do well to invest not just in red lines but also in firebreaks and indirect communication channels — whether through the United Nations Interim Force in Lebanon, Russia, or the UN-mediated Israeli-Lebanese official military channel. For example, in January 2015 Israel and Hizballah appeared to be on the verge of a severe escalation after Hizballah killed two IDF soldiers in retaliation for an Israeli attack on several of its men in Syria. Fearing further deterioration, the two parties were quick to exchange reassuring messages through the United Nations. Improving communication could minimize the risk of misunderstanding and prevent an unwanted but limited escalation in Syria or even in the Lebanese arena from spiraling into an all-out war. In addition, an untapped opportunity still remains for Israel and Lebanon to solidify the stability along their border: Jerusalem should declare that it is willing to cooperate with the United Nations to turn Hariri’s unanswered call for a “permanent ceasefire” into a diplomatic reality.

Daniel Sobelman is Assistant Professor of International Relations, the Hebrew University of Jerusalem, Israel.

Image: Johnny Zoo/Wikimedia Commons