12-Day War

On June 13, 2025, Israel conducted a major operation against Iran. The anticipated attack, which targeted nuclear facilities, military sites, and regime infrastructure, followed nearly two years of war between Israel and Iran-backed militant groups that also saw two direct confrontations between Israel and Iran in 2024. As fighting increased on both sides, the United States got involved, targeting the most critical and fortified sites in Iran’s nuclear program, which Israel was unable to destroy with its own arsenal. A ceasefire was announced on June 24, bringing the 12-day war to an end.

• U.S.-Iran Relations: A timeline of betrayal, rhetoric, and bloodshed.

Conflict between Iran, Israel, and the United States flared up anew in February 2026, particularly after the 2026 Iranian protests signaled widespread frustration with the regime. The U.S., along with Israel, launched a major operation targeting sites across Iran. This time, the U.S. said its goal was to disable Iran’s nuclear efforts, disarm its ballistic missile capabilities, and also prompt change in government leadership. On the first day of operations, supreme leader Ali Khamenei was killed in the U.S.-Israeli strikes. 

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Background

Once allies—from 1948 to 1979—Israel and Iran became bitter enemies after the Iranian Revolution of 1979, in which the new, anti-colonial Islamic regime blamed the United States and Israel for the region’s greatest grievances. Matters escalated significantly in the early 2000s when Iran was revealed to have a suspiciously secret nuclear program and, as U.S.-led forces toppled the regime of Saddam Hussein in Iraq that fiercely opposed Iran, Iran expanded its reach across the region (see Axis of Resistance).

Israel-Hamas War and Israel’s window of opportunity

In 2024, following the Hamas-led attack on Israel on October 7, 2023, Israel significantly diminished Iran’s reach in the Middle East in its retaliation against Iran’s major allies. Although the primary theater for conflict that year was Israel’s war in the Gaza Strip, Israel also decapitated the Iran-aligned group Hezbollah in Lebanon in September–November, which in turn facilitated Ahmed al-Sharaa’s toppling of Pres. Bashar al-Assad in Syria in December. When Israel and Iran twice exchanged direct strikes—first in April 2024 and again in October—Iran downplayed the effectiveness of Israel’s missiles at striking its military targets, and Iran’s barrage of missiles toward Israel largely failed to cause significant damage or casualties. According to analysts, these incidents not only damaged Iran’s military capabilities but also revealed its vulnerabilities in defending strategic military assets as well as its limitations in penetrating Israel’s defenses. With Iran’s Axis of Resistance dismembered and its weaknesses laid bare, top Israeli figures saw a window of opportunity to take out Iran’s nuclear capabilities and, potentially, its regime.

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Israeli strikes on Iran

Over the next several months, Israeli officials sought support from the United States, its most important military ally, to strike Iran in an operation planned for April 2025. Donald Trump, who returned to the U.S. presidency in January, asked Israel to refrain from any strikes so that his administration could pursue a peaceful new nuclear deal with Iran. But when negotiations faltered in June and Iran sought to ramp up its uranium enrichment, Israel launched an attack early on June 13 in coordination with operations conducted by its Mossad intelligence agency. The operation’s opening salvo, conducted by 200 Israeli fighter jets on more than a hundred targets, killed top military leaders—most notably Hossein Salami, the head of the Islamic Revolutionary Guard Corps (IRGC); Mohammed Bagheri, the chief of staff of the armed forces; and Amir Ali Hajizadeh, the commander of the IRGC’s air force—as well as several nuclear scientists. The attacks also caused significant damage to Iran’s primary uranium enrichment facility, at Natanz, north of Isfahan, as well as to its air defense and missile systems. Iran’s initial response, in the hours following Israel’s first strikes, was to send about a hundred drones toward Israel, but it soon escalated its attacks with hundreds of ballistic missiles. Israel continued to bombard military sites and nuclear facilities in Iran, including the nuclear facility complex just southeast of Isfahan and the headquarters of Iran’s ministry of defense in Tehran. An Iranian missile also made impact in the Kirya area in central Tel Aviv that houses military facilities such as the headquarters for the Israel Defense Forces (IDF), although no significant damage was reported. Residential buildings in both countries were also struck in the crossfire, killing hundreds of civilians in Iran and dozens of others in Israel in the initial days of conflict.

United States strikes Fordow and other nuclear facilities

Although Israeli air power was capable of setting back Iranian nuclear development, it did not have the capability to destroy its nuclear program altogether. The enrichment facility at Fordow, which contained the most advanced centrifuges capable of enriching weapons-grade uranium, was located deep underneath a mountain and its destruction required the use of U.S. GBU-57 A/B “bunker buster” bombs delivered by B-2 bombers. Despite initial hesitation to participate in the conflict, the United States struck nuclear facilities in Fordow, Natanz, and Isfahan on June 22, an attack which Trump said was intended to be a limited, one-off mission. The following day Iran retaliated by launching missiles at Al Udeid Air Base in Qatar, which hosts U.S. forces, although it warned Qatar and the United States about the attack in advance. The attack appeared to be symbolic and did not cause any injuries. A preliminary, low-confidence report from the U.S. Defense Intelligence Agency (DIA)—in what the Trump administration characterized as a “political” leak to the press—assessed that Iran had moved much of its stockpile of enriched uranium before the U.S. strikes took place and that the strikes, which did not collapse the underground facilities according to the report, set back Iran’s ability to produce nuclear weapons by only a matter of months. The following day John Ratcliffe, the director of the Central Intelligence Agency (CIA), said new information indicated severe damage to the nuclear facilities that would take years for Iran to rebuild.

Ceasefire agreement

A ceasefire agreement was announced on June 24, 2025 by Trump, who reported that the agreement included 12 hours of cessation of hostilities by Iran followed by another 12 hours of cessation of hostilities by both Iran and Israel. After the completion of both cycles without incident, the conflict would officially come to an end. Although serious violations took place in the initial hours of the ceasefire, killing 16 people in Iran and 4 in Israel, it continued to hold under U.S. pressure.

2026 Iran conflict

The United States, with Israel, launched major attacks on Iran in February 2026, citing Iran’s nuclear ambitions and a desire for change in government as catalysts for the moves. Iran retaliated with missile strikes against American bases in the region, opening a broader conflict that embroiled much of the region.

Supreme Leader Khamenei was killed in the attacks, and U.S. Pres. Donald Trump urged Iranians to rise up against their government: 

“When we are finished, take over your government. It will be yours to take. This will be probably your only chance for generations,” Trump said hours after the attacks began on February 28, 2026.