Another round of fighting between Israel and Hezbollah is certainly likely, but I don’t consider it inevitable, particularly in the short term. There are several reasons for this.
The first is that we have to understand the importance of Hezbollah in Iranian strategy at present. The party is not there to get caught up in repeated conflicts with Israel, let alone a new Lebanese civil war. It is mainly there to act as an Iranian deterrent against an Israeli attack on Iran’s nuclear facilities, and more generally as a valuable lever in the Levant to use against Israel and the United States. In that context, war poses risks. With every conflict, the party loses some of its deterrence capability; at the same time, a conflict may impose unbearable human costs on the Shiite community, in such a way that Hezbollah’s ability to fight is further eroded. (Indeed, we are already in that situation today.) And, any new war will have deeply negative repercussions on Hezbollah’s domestic position, as a majority of Lebanese and Lebanese political forces reject the idea of again entering into a devastating war with Israel.
Add to that the time factor. Hezbollah is probably not yet ready to fight a war with Israel today, despite what Hasan Nasrallah has said in public recently. Shiites are deeply anxious about a new conflict a mere two years after the summer 2006 war; Hezbollah’s defensive infrastructure north of the Litani River appears to be incomplete; and the party cannot guarantee geographical continuity between south Lebanon and the southern and northern Bekaa Valley, though this is not essential for it to fight. These are all reasons why Hezbollah has to be careful in how it retaliates for the assassination of Imad Mughniyah. Provoking a major Israeli offensive is almost certainly not something Nasrallah wants to do today.
As for Nasrallah’s claim that the next war will involve an Israeli ground offensive, that’s not necessarily true. Israel has the potential to once again primarily employ air power to wreak the destruction it did in 2006—but also in 1993 and 1996—provoking a massive exodus of Shiite civilians and bombing infrastructure targets. This gruesome policy would create a humanitarian catastrophe that would mainly affect Hezbollah, and the party would find it difficult to respond in such a way that it could impose a balance of terror on Israel. Meanwhile, Lebanese anger with the party would have only heightened, further undercutting its support in society.
What about Israel? There may be a rationale for striking against Hezbollah before it’s too late. However, the Israeli priority today appears to be less Lebanon than Iran and its nuclear capacity. Lebanon is a sideshow—an important one, but a sideshow nonetheless. Paradoxically, Hezbollah’s reluctance to launch a war might encourage Israel to avert a conflict too. Why? Because both sides would calculate in terms of costs and benefits. Israel knows that it would be very difficult to score a knockout blow against Hezbollah in Lebanon. It does not want to risk getting caught up in a wider regional war via Lebanon. And a new Lebanon war would only make it more difficult to strike against Iran.
Given such uncertainty, each side is more likely to focus on its fundamental aims: Israel, on neutralizing Iran’s nuclear capacity; Hezbollah on partly deterring an Israeli attack against Iran. That means both may well try to avoid an unmanageable escalation in Lebanon.
Still, the most likely cause of war remains miscalculation. Here the risks are higher. Too devastating a Hezbollah response to the Mughniyah killing might provoke a fierce response from Israel. Conversely, another assassination of a Hezbollah official could prompt Hezbollah to react in increasingly less calculating ways, making a clash more probable. Even an Israeli offensive against Gaza may force Hezbollah to take steps in southern Lebanon to back its brethren in Hamas, and this may widen the conflict with Israel.
Then again, Hezbollah would have to calculate whether this might lead to a repeat of 2006, which also followed a Hamas raid in Gaza, the net result of which was to Hezbollah’s considerable disadvantage—all claims to a “divine victory” notwithstanding.