On July 30, an Iranian drone attacked the Mercer Street—an oil tanker operated by an Israeli-owned company—killing one British and one Romanian citizen, thus escalating Tehran’s ongoing clandestine maritime war with the Jewish state. As the “ultimate guarantor of freedom of navigation in the world’s oceans,” the U.S. “shares with other countries responsibility for protecting this essential principle,” writes Robert Satloff. Yet the Biden administration is likely reluctant to retaliate, out of fear that doing so will derail the already stalled talks to revive the 2015 nuclear agreement. Such thinking, Satloff explains, gets things exactly backwards:

Tehran and its proxies have been aggressively testing the White House—both with attacks on shipping in the Gulf and via proxy attacks by Iranian-backed militias on U.S. targets in Iraq—without learning precisely where Washington draws a line. The most common U.S. response so far has been to hit pro-Iranian militia sites in northeast Syria, which sends a message to Tehran that the United States is avoiding conflict, not deterring it. Until that message is clarified, Iran is likely to continue ratcheting up its attacks.

An effective U.S. response to the Mercer Street attack . . . would be a far cry from pinprick action against proxy groups and mere public declarations, both of which only invite further Iranian testing. . . . [A firmer] response would bolster deterrence [and] signal to America’s regional allies that shrinking the U.S. military footprint in the Middle East does not mean Washington is shirking its role as a guarantor of international norms, including the all-important freedom of maritime navigation. And of special concern to the Biden administration: an effective response would have the benefit of addressing one of the . . . reasons for the impasse in [nuclear] negotiations.

Some in the Biden administration will make the opposite case—that an effective reply to Iran’s deadly shipping attack will spook the Tehran regime, confirm to the supreme leader and his new president that the United States is a hostile power not to be trusted, and even fuel an escalation of violence and confrontation. This is a legitimate concern. Far more likely, however, is that Iran will view U.S. inaction as an invitation for further testing, itself raising the prospect of even more lethal attacks than the one on the Mercer Street and further poisoning the potential for diplomacy.

Early Friday morning, Israel attacked military installations near the Iranian cities of Isfahan and nearby Natanz, the latter being one of the hubs of the country’s nuclear program. Jerusalem is not taking credit for the attack, and none of the details are too certain, but it seems that the attack involved multiple drones, likely launched from within Iran, as well as one or more missiles fired from Syrian or Iraqi airspace. Strikes on Syrian radar systems shortly beforehand probably helped make the attack possible, and there were reportedly strikes on Iraq as well.

Iran itself is downplaying the attack, but the S-300 air-defense batteries in Isfahan appear to have been destroyed or damaged. This is a sophisticated Russian-made system positioned to protect the Natanz nuclear installation. In other words, Israel has demonstrated that Iran’s best technology can’t protect the country’s skies from the IDF. As Yossi Kuperwasser puts it, the attack, combined with the response to the assault on April 13,

clarified to the Iranians that whereas we [Israelis] are not as vulnerable as they thought, they are more vulnerable than they thought. They have difficulty hitting us, but we have no difficulty hitting them.

Nobody knows exactly how the operation was carried out. . . . It is good that a question mark hovers over . . . what exactly Israel did. Let’s keep them wondering. It is good for deniability and good for keeping the enemy uncertain.

The fact that we chose targets that were in the vicinity of a major nuclear facility but were linked to the Iranian missile and air forces was a good message. It communicated that we can reach other targets as well but, as we don’t want escalation, we chose targets nearby that were involved in the attack against Israel. I think it sends the message that if we want to, we can send a stronger message. Israel is not seeking escalation at the moment.