What to Know About the Israeli Strike on Iran

In a wave of attacks, the Israeli military struck the Natanz nuclear facility, military bases, and other targets in Iran, and also assassinated Iran’s three top military leaders among many other senior military officials and several nuclear scientists. Israel’s military strikes are likely to set back Iran’s nuclear program, but parts of the program will remain intact to varying degrees, and Iran will seek to retaliate. The resulting mess might lead the United States to become involved, despite the Trump administration’s desire to avoid attacking Iran.

Iran has had an active nuclear program for decades, and in recent years, the country has appeared closer than ever to achieving a nuclear weapon. While Tehran’s progress was once sporadic, it has steadily developed its enrichment facilities and other nuclear weapon components. In 2015, the Obama administration negotiated the Joint Comprehensive Plan of Action, which froze the program, but President Trump withdrew from it in 2018, declaring it a “bad deal.” Since then, Iran has enriched uranium to 60 percent, a high level from which the country could easily reach the 90 percent level needed for weapons-grade material.

Israel has long seen an Iranian nuclear weapon as an existential threat, but despite repeated warnings, for many years it avoided striking Iran for several reasons. Benjamin Netanyahu, though often talking tough, was cautious regarding the use of military force during most of his time as prime minister. Before the October 7, 2023, terrorist attacks, a conflict between the two countries seemed to have several powerful deterrents:

• a Hezbollah response that would involve massive rocket and missile salvos on Israel;
• direct Iranian retaliation, including missile and drone strikes from its own arsenals;
• the possibility that other Iranian proxies in the region, such as Hamas, would join in coordinated attacks; and
• the danger that Tehran could resort to international terrorism targeting U.S. and Israeli interests.
   

The United States consistently opposed a strike as well, doubting Israel’s ability to carry it out alone and unwilling to commit U.S. forces to support such an operation. U.S. leaders also feared that a strike would destabilize the Middle East and lead Iran to redouble its efforts to seek a nuclear weapon.

Israel today, however, is not the country it was before the October 7 attacks. In a short but fierce conflict, Israel devastated Hezbollah with an impressive intelligence and military campaign. Israel is stuck in Gaza with unproductive military operations there, but Hamas is far weaker than it was before. In addition, Iran’s attempts to attack Israel directly in April and October 2024 were dismal failures. Israel—with U.S. help—intercepted many of the missiles and drones and suffered few casualties. Israel’s own response against Iran, while measured, involved striking well-defended targets such as air defense systems, demonstrating Israel’s potential reach. Israel also demonstrated superb intelligence penetration of both Hezbollah and Iran in its attacks, suggesting that it may have excellent targeting information on Iran’s nuclear program and, if necessary, Iran’s leadership. Thus, Iran’s deterrent is far weaker than it was before October 2023.

Perhaps most importantly, Israel’s risk tolerance has changed. Before the attack, polling indicated that most Israeli Jews favored military attacks on Iran, viewing Tehran as responsible for the October 7 attacks and for strengthening Hamas, Hezbollah, and the Houthis in Yemen. After October 7, Israel showed its willingness to go on the offense in Gaza and Lebanon, the increasingly critical views of the international community be damned, and it may see attacking Tehran in the same light.

It is not clear if the attack will truly devastate Iran’s program in the long term. The June 1981 Israeli attack on the Osirak reactor in Iraq was initially seen as a success. However, reviews of captured Iraqi records indicate it triggered a massive covert buildup and increased long-term proliferation risk. The long-term consequences of an Israeli strike on Iran could be similar.

It is unclear that the attack will do more than marginal damage in the short term. Iran is far from Israel, making it harder to sustain military operations over Iranian territory. It is believed that key nuclear sites in Iran, such as Natanz, are hardened, with some under layers of reinforced concrete, and Fordow is constructed within a mountain. Some of these facilities may require multiple strikes of Israeli munitions. Although Israel has shown it can overcome Iranian air defenses, some of these systems, such as the Russian S-300PMU-2, are formidable, requiring additional attacks to disrupt and risking the loss of Israeli aircraft. Regional states like Saudi Arabia and the United Arab Emirates, while no friends of Iran, do not want to support Israeli military operations openly. Thus, it is hard for Israel to sustain operations, making it more difficult to destroy the well-protected Iranian facilities, though certainly they would do some damage.

Iran will probably seek to retaliate even though its proxies are far weaker and are licking their wounds. Iran may still push them to attack Israel anyway, though how much of a punch they pack after repeated blows from Israel is unclear, and Hezbollah in particular would be reluctant to restart a fight it knows it would probably lose. Tehran might also turn to international terrorism, having worked with Hezbollah in the past to attack Jewish and Israeli targets in Europe, South America, and elsewhere in the past in its confrontations with Israel.

The United States could easily get sucked into this conflict, even if it opposes the Israeli strike. Given the close relationship between Jerusalem and Washington, Tehran might believe that the United States helped the attack with intelligence and weapons, even if, this time, the United States played no role (so far, the U.S. role is not clear). Before Israel’s attack, Iran threatened to attack U.S. bases in the Middle East in response to an Israeli strike, and it could also use terrorism against U.S. targets. If regional Arab allies help Israel—or if Iran believes they did so—they too might be targets, providing another impetus for the United States to join in the fray.

Washington might also feel compelled to finish the Israeli job—and Israel might be banking on such a U.S. response. Unlike Israel, the United States has bases near Iran, and it could conduct more devastating strikes on nuclear-related facilities as well as degrade Iranian air defenses severely. Although the Trump administration might not want to attack Iran, it might feel that doing so is better than allowing Iran to rebuild its nuclear program. Such a U.S. response is especially likely if Iran retaliates against U.S. as well as Israeli targets.

Daniel Byman is the director of the Warfare, Irregular Threats, and Terrorism Program at the Center for Strategic and International Studies in Washington, D.C.