When terrorists in Gaza fired some 450 rockets at Israel last month, the Iron Dome anti-missile system kept the damage to a bare minimum, intercepting at least 86 percent of the incoming projectiles. But it would be both more difficult and more expensive to maintain such a success rate if Hamas and Islamic Jihad were to succeed in upgrading their missiles with precision-guidance technology. The consequences would be even worse if these groups were joined by the various Iran-backed guerrillas in Syria, Lebanon, Iraq, and Yemen, at least some of whom already have such weapons. Jonathan Schanzer writes:

[W]ith enough precision guided missiles (PGMs) fired at the same target, Iran’s proxies may be able to outmaneuver, outsmart, or overwhelm Israeli missile-defense systems, with the result that one or more rockets would get through. Hamas already claims to be able to do this with its unguided rockets. Such claims are dubious now. But in the future, if the intended target is the chemical plant in Haifa, the Kiryah (Israel’s defense headquarters) in Tel Aviv, Ben Gurion International Airport, or a Tel Aviv office building, the results could be catastrophic.

Israel’s military brass would much rather destroy PGMs on the ground than intercept them in the air. One problem they have is patrolling the vast territory Iran controls to build, store, and launch its munitions.

With PGMs, the era of Iron Dome’s total dominance may come to an end. This does not mean that the Israelis will stop using this remarkable system to protect its citizens from incoming rockets. But barring significant improvements to counter PGMs, Iron Dome may no longer provide the Israeli leadership with the luxury of time to weigh their options when they must respond to a hailstorm of precision strikes.

Should PGMs pierce Israel’s defenses and hit more of the intended targets, the Israeli public will demand a response. The political and military leadership will be forced to respond more rapidly and with greater force. This will increase the odds of mistakes on the battlefield and thus the odds of escalation. And if PGMs are fired from multiple locations, the natural result will be a multifront war.

Surveying news websites and social media on Sunday morning, I immediately found some intelligent and well-informed observers arguing that Iran deliberately warned the U.S. of its pending assault on Israel, and calibrated it so that there would be few casualties and minimal destructiveness, thus hoping to avoid major retaliation. In other words, this massive barrage was a face-saving gesture by the ayatollahs. Others disagreed. Brian Carter and Frederick W. Kagan put the issue to rest:

The Iranian April 13 missile-drone attack on Israel was very likely intended to cause significant damage below the threshold that would trigger a massive Israeli response. The attack was designed to succeed, not to fail. The strike package was modeled on those the Russians have used repeatedly against Ukraine to great effect. The attack caused more limited damage than intended likely because the Iranians underestimated the tremendous advantages Israel has in defending against such strikes compared with Ukraine.

But that isn’t to say that Tehran achieved nothing:

The lessons that Iran will draw from this attack will allow it to build more successful strike packages in the future. The attack probably helped Iran identify the relative strengths and weaknesses of the Israeli air-defense system. Iran will likely also share the lessons it learned in this attack with Russia.

Iran’s ability to penetrate Israeli air defenses with even a small number of large ballistic missiles presents serious security concerns for Israel. The only Iranian missiles that got through hit an Israeli military base, limiting the damage, but a future strike in which several ballistic missiles penetrate Israeli air defenses and hit Tel Aviv or Haifa could cause significant civilian casualties and damage to civilian infrastructure, including ports and energy. . . . Israel and its partners should not emerge from this successful defense with any sense of complacency.