Israel's preemptive strike doctrine is likely lowering its political threshold for action amid growing threats from Iran and its network of allies, but this shift is unlikely to deter future strikes on Israel and will instead increase the risk of sparking a larger regional war. On Aug. 25, the Israel Air Force (IAF) announced it had launched a large preemptive strike on Hezbollah's arsenal and rocket launchers to prevent a mass strike on Israel. Israel claimed that the strikes helped weaken the barrage of missiles that Hezbollah launched into Israel shortly thereafter, and was trumpeted by Israeli politicians and defense figures as a successful operation. The actual damage on the ground was less clear, with limited Hezbollah casualties suggesting a marginal impact on the contours of the Lebanese militant group's Aug. 25 attack against Israel, but the IAF strike nevertheless indicated that Israel's preemptive defense doctrine had moved into a new phase in its regional confrontation with Iran and its allies over the ongoing Gaza war. The Israeli strikes came after weeks of intensifying public pressure, particularly from right-wing politicians, for Israel to act against Hezbollah and Iran rather than await their retaliations for last month's assassinations of Hamas political chief Ismail Haniyeh in Tehran and top Hezbollah commander Faud Shukr in Beirut.

• Israel has a long history of preemptive attacks as part of its military doctrine. Most famously, in 1967 during the Six-Day War, it conducted early air strikes on the Egyptian Air Force to prevent Egypt from being able to use long-range bombers and develop air superiority. Israel has also long threatened to strike Iran preemptively should Tehran decide to develop a nuclear weapon. But Israel has demurred from imposing a similar policy against Iran, Hezbollah and Yemeni Houthi militants in the course of the current regional confrontation, for fear that preemptive strikes might worsen security conditions and isolate Israel from its allies like the United States, rather than interdict attacks. Instead, Israel has focused on preemptive action largely in Syria and more rarely against Iraq, with some covert action in Iran itself. 
• The preemptive strikes on Hezbollah were reportedly conducted in coordination with U.S. intelligence, showing the United States also gave its political backing to the operation. 
• Shortly after the preemptive strikes, Hezbollah carried out a rocket and drone barrage against Israel on Aug. 25, which the Lebanese militia said was part of its long-awaited retaliation for the July 30 killing of Shukr in Beirut. Israel claimed its preemptive aerial campaign destroyed thousands of Hezbollah rockets on the ground before the group was able to fire them, though Hezbollah disputed this number while admitting some launchers had been destroyed. 

Israel's Preemptive Strike Doctrine

Israel's preemptive strike doctrine is based on the idea of attacking imminent military threats to the country. But the definition of ''imminent'' is partially a military consideration and partially a political one, with the military assessing whether a preemptive strike is feasible from a logistical and military standpoint, and with the government's security cabinet assessing whether a strike is worth the risk of potential escalation and diplomatic backlash. Israel has historically often carried out preemptive military operations against targets it believes will not spark significant escalations, as opposed to striking all opponents who are preparing to attack Israel. This can be evidenced by Israel's long history of conducting assassinations and strikes against regional nuclear programs in rival countries that were not well-positioned to conduct expansive retaliations. In 1983, for example, Israel bombed Iraq's Osirak nuclear reactor at a time when Iraq was poorly positioned to retaliate due to its deep involvement in the then Iran-Iraq War. In 2007, Israel also destroyed Syria's nascent nuclear program, but Syria lacked the military power and regional backing to escalate against Israel in response. However, Israel has been much more hesitant to conduct a preemptive strike on Iran's nuclear program, as it has assessed that Iran has both the willingness and capability to respond with a significant military escalation. For the same reason, Israel was also reportedly wary of assassinating former Iranian Quds Force General Qassem Soleimani, who was killed in a U.S. strike in January 2020. 

With greater political backing, the Israel Defense Forces (IDF) will likely conduct preemptive strikes against Yemeni Houthis and Iran-backed militias in Syria and Iraq that are preparing their own rounds of retaliation against Israel. In response to the Houthis' deadly July 19 drone attack on Tel Aviv, Israeli jets on July 20 bombed the Houthi-controlled port of Hodeidah in Yemen, demonstrating the IAF's capabilities and intent to strike Yemen in response to Houthi provocations. The Houthis have threatened to launch reprisal attacks for the Hodeidah strike, as well as for the July 31 killing of Hamas' political chief in Tehran. But instead of awaiting this retaliation, Israel is increasingly likely to conduct preemptive strikes against the Houthis should the Israeli government assess such strikes would weaken attacks against Israel. Additionally, should the Houthis' impending barrage be coordinated with militias in Syria and Iraq, these groups would also likely be targets of IDF preemptive strikes. These groups' more limited means would impede their ability to quickly conduct reprisal attacks against Israel itself in the aftermath of such preemptive strikes, thereby reducing the likelihood of regional escalation. This lower risk of escalation would also make the United States more willing to back such preemptive action, further incentivizing Israel to strike these actors first. 

• Israel already routinely conducts strikes on Iranian-backed forces in Syria, where it has largely free reign, and has also previously struck targets in Iraq.
• Israel is still awaiting Iran's pledged response to the July 31 killing of Hamas' political chief in Tehran. It is unclear how Iran's long-threatened retaliation will play out, but one possible strategy could see Iran utilize its proxies and allies to conduct a wave of attacks on Israel, independent of an attack from Iran itself, to demonstrate the risks of further escalation without tipping the region over into general war. 

Israel may also conduct more preemptive strikes against Hezbollah in the course of future rounds of escalation with the group, but this would create a greater risk of potential miscalculations that could result in another general war between the Lebanese militants and Israel. Given the public success of its Aug. 25 strikes on Hezbollah, Israel's government would be politically incentivized to repeat a similar operation if there are signs Hezbollah is preparing to conduct another mass barrage against Israel that could overwhelm the country's air defenses and inflict significant casualties. Israel could soon face this prospect, as Hezbollah has suggested that its retaliation is not over and may still have further rounds. However, if Hezbollah signals that it is going to carry out an attack larger than the one it launched on Aug. 25, the IDF might need to target more high-value systems, such as precision-guided missiles and command and control centers, in order to interdict such a barrage. This, however, would carry a greater risk of Israel striking targets that are politically sensitive to the militant group, which could spur them into a greater cycle of escalation and retaliation that would lead to a general war.

• Further rounds of Hezbollah-Israeli confrontations may be triggered by accidental strikes as well. On July 28, a Hezbollah rocket struck a football field in the Golan Heights, killing 12 Israelis, mostly children. Hezbollah disavowed the strike on the football field, which was unlikely the direct target of its operation, given the group's political and strategic goals in the area. But the incident nonetheless prompted Israel to assassinate Hezbollah commander Faud Shukr two days later. 

Israel is less likely to conduct preemptive strikes against Iran due to the greater risk of regional escalation. However, as future rounds of Israeli-Iranian confrontations take place without precipitating a general war, Israel's government may conclude that preemptive strikes on Iran carry an acceptable risk, especially if Iran hawk Donald Trump is reelected U.S. president. Iran has signaled it does not intend to conduct strikes that would precipitate a general war, which suggests that its still-impending retaliation for Israel's killing of a Hamas leader in Tehran will be similar to the ballistic and drone barrage Iran launched against the country in April. The April 13 barrage was notable in that it marked the first time Iran had ever explicitly and directly attacked Israeli territory, but the strike only caused limited damage to an Israeli air base while incidentally killing one civilian, as it was designed to showcase Iran's ability to cause damage rather than overwhelm Israel's air defenses. The fact that Iran's looming retaliation is expected to be similar in scope — and thus unlikely to be gauged to overwhelm Israeli air defenses — weakens Israel's incentive to take the risk of interdicting such an attack by launching preemptive strikes on Iranian territory. Nevertheless, as Israel remains unlikely to be deterred from further covert and overt escalation, and future rounds of Iranian-Israeli confrontation are probable, Israel will be increasingly willing to conduct preemptive strikes against sites in Iran in an attempt to weaken further rounds of Iranian attacks. This will become especially likely if former U.S. President Donald Trump wins another term in November, given Trump's more hawkish views on Iran and the escalatory actions he took against the country while in office. However, preemptive Israeli strikes on Iran would likely only strengthen Iranian hard-liners' arguments to escalate against Israel more significantly, as well as to escalate against the United States and its regional Arab allies. As a result, although Israeli preemptive strikes against Iran may successfully diminish the scale of certain attacks, they will also increase the risk that Tehran decides to expand its regional campaign against Israel and its allies, while also feeding into Iran's drive toward the development of a nuclear weapon.

• Trump has claimed that his hawkish anti-Iran policies prevented Iranian attacks against Israel during his presidency. Should he return to the White House, this suggests Trump would resume such hard-line policies toward Iran, which included the U.S. assassination of Soleimani. Trump's hawkishness also emboldened Israel to escalate its covert campaign against Iran during Trump's term, particularly in Syria.