In recent months, Hassan Nasrallah, the leader of Iran’s Lebanon-based proxy army, has been speaking about the Jewish state with even greater bellicosity than usual, suggesting that, with the war in Syrian winding down, he might be readying to turn his attention southward. Most experts believe the subsequent conflict could be far deadlier than in 2006: an all-out attack by Hizballah could overwhelm, at least temporarily, Israel’s sophisticated missile-defense systems, especially if it were coupled with coordinated rocket fire from Gaza. By the same token, the IDF’s response would be devastating for Lebanon. Thomas Donnelly comments:

Israel has not faced such a powerful threat since the 1973 war, and confronting the Iran-Hizballah-Assad coalition will tax the IDF heavily. . . . [Such a conflict’s] daunting tactical challenges also, as in the past, generate strategic and geopolitical problems. The perception of victory often counts more than the battlefield result, both in the region and in the larger international contest.

Nasrallah excels at spinning defeat into victory. [In 2006, notwithstanding Hizballah’s considerable losses], survival became triumph, a bit of propaganda that caught on in outlets such as the Economist, which declared, “Nasrallah wins the war.” By now even many Israelis, especially on the political left, concur. . . . The standard of victory for Israel remains almost impossibly high.

Despite the gloomy view of the past and the foreboding about the future, it is also the case that since 2006 Israel’s northern border has been remarkably quiet. That’s even more remarkable considering the chaos that’s ripped Iraq and Syria apart and catapulted Iran to the fore. This is a ceasefire worth preserving. It particularly behooves the United States to try to do so. . .

At the same time, the looming war presents an important opportunity. . . . Should deterrence fail and conflict resume, it will be important for the United States to back the Israelis clearly and forcefully. . . . A decisive Israeli victory against the Tehran-backed Hizballah forces would be an unparalleled opportunity to stem the regional Iranian tide, thereby serving a prime U.S. national-security interest. Such a victory would both reassure and relax America’s Arab allies, particularly in Saudi Arabia, the Gulf states, and Egypt—those most nervous about a flagging U.S. commitment in the Middle East. It would also remind the world that, despite Vladimir Putin’s meddling, the United States remains the most powerful external force in the region. . . . Just as Israelis have begun to prepare themselves for this [prospective conflict], so should [the U.S.].

Earlier this month, an operative working for, or in conjunction with, Hizballah snuck across the Israel-Lebanese border and planted a sophisticated explosive near the town of Megiddo, which killed a civilian when detonated. On Thursday, another Iranian proxy group launched a drone at a U.S. military base in Syria, killing a contractor and wounding five American soldiers. The former attack appears to be an attempt to change what Israeli officials and analysts call the “rules of the game”: the mutually understood redlines that keep the Jewish state and Hizballah from going to war. Nadav Pollak explains how he believes Jerusalem should respond:

Israel cannot stop at pointing fingers and issuing harsh statements. The Megiddo attack might have caused much more damage given the additional explosives and other weapons the terrorist was carrying; even the lone device detonated at Megiddo could have easily been used to destroy a larger target such as a bus. Moreover, Hizballah’s apparent effort to test (or shift) Jerusalem’s redlines on a dangerous frontier needs to be answered. If [the terrorist group’s leader Hassan] Nasrallah has misjudged Israel, then it is incumbent on Jerusalem to make this clear.

Unfortunately, the days of keeping the north quiet at any cost have passed, especially if Hizballah no longer believes Israel is willing to respond forcefully. The last time the organization perceived Israel to be weak was in 2006, and its resultant cross-border operations (e.g., kidnapping Israeli soldiers) led to a war that proved to be devastating, mostly to Lebanon. If Hizballah tries to challenge Israel again, Israel should be ready to take strong action such as targeting the group’s commanders and headquarters in Lebanon—even if this runs the risk of intense fire exchanges or war.

Relevant preparations for this option should include increased monitoring of Hizballah officials—overtly and covertly—and perhaps even the transfer of some military units to the north. Hizballah needs to know that Israel is no longer shying away from conflict, since this may be the only way of forcing the group to return to the old, accepted rules of the game and step down from the precipice of a war that it does not appear to want.