The Twelve-Day War was an armed conflict between Iran and Israel which lasted from 13 to 24 June 2025. It began when Israel bombed military and nuclear facilities in Iran in a surprise attack, assassinating prominent military leaders, nuclear scientists, and politicians, killing civilians, and damaging or destroying air defenses. Iran retaliated with over 550 ballistic missiles and over 1,000 suicide drones, hitting civilian population centers, one hospital and at least twelve military, energy, and government sites. The United States intercepted Iranian attacks and bombed three Iranian nuclear sites on 22 June. Iran retaliated by firing missiles at a US base in Qatar. On 24 June, Israel and Iran agreed to a ceasefire under US pressure.
The war followed a decades-long proxy conflict in which Iran supported an Axis of Resistance against Israeli and US interests in the region. Iran's development of nuclear enrichment capabilities has been an international controversy for decades, with Israel and its allies seeking to prevent Iranian nuclear weapons development. In 2015, under the Joint Comprehensive Plan of Action (JCPOA), six countries lifted sanctions on Iran, which froze its nuclear program. In 2018, US president Donald Trump unilaterally withdrew from the plan. Iran began stockpiling enriched uranium and largely suspended International Atomic Energy Agency (IAEA) monitoring. Following the October 7 attacks in 2023, both Hamas and Hezbollah entered into open conflict with Israel. In April 2024, Israel bombed Iran's consulate in Damascus, Syria, killing senior Iranian military officials. Direct conflict continued in April and October of 2024. The day before Israel started the Twelve-Day War in June 2025, the IAEA declared Iran non-compliant with its nuclear obligations in a resolution put forward by the United States, United Kingdom, France, and Germany.
Israel's attacks, which reportedly involved commando units and Mossad operatives in Iran, killed several of Iran's military leaders, leaders of the Islamic Revolutionary Guard Corps (IRGC), and at least 10 leading nuclear scientists. The war saw internet blackouts by the Iranian government. Israeli and US airstrikes damaged the nuclear facilities at Natanz, Isfahan, and Fordow, damaging them extensively. Iran suspended cooperation with the IAEA, which it said had passed information about nuclear facilities and scientists to Israel. Iran's total death toll has been estimated at between 1,060 and 1,190; thousands were wounded, tens of thousands were displaced, and the government ordered internet blackouts. Israel struck high-rise buildings, including apartments. Iranian missiles struck military and government sites, apartments, a research center, and a hospital.
The United Nations and most countries expressed deep concern over Israel's strikes and called for a diplomatic solution. The strikes were condemned by many countries, including most Muslim-majority and Arab states. The International Commission of Jurists and some other legal scholars saw the Israeli strikes as a violation of international law. Meanwhile, Argentina, Germany, Ukraine, and the United States said the strikes on Iran were justified to prevent nuclear proliferation and said Iran should agree to a nuclear deal promptly. Nine months later, on 28 February 2026, Israel and the United States launched strikes on Iran, beginning the 2026 Iran war.
Donald Trump first labeled the conflict as the "12 day war" in his announcement of a ceasefire agreement between Israel and Iran on 23 June 2025. AP News speculated the title was a reference to the 1967 Six-Day War, fought between Israel and a coalition of Arab states. A few days afterwards, American academic Howard Stoffer also compared the two wars to each other, and Reuters began using "12-day war" as a descriptive title; however, some experts initially doubted that Trump's coining would catch on. Ultimately, the standardized name "Twelve-Day War" or "Twelve Day War" entered into common usage by late 2025. In Iran, however, the conflict is labeled as the "Second Imposed War".
Israel maintained a close relationship with the Pahlavi monarchy until the Iranian Revolution, when the monarchy was ousted and replaced by an anti-Western theocratic Islamic republic led by Ruhollah Khomeini. Ever since, Iran's government has repeatedly pledged to destroy Israel. Israel considers the Iranian nuclear program an existential threat, fearing that Iran will develop a nuclear weapon.
In 2024, Israel and Iran attacked each other openly and directly for the first time following decades of proxy war. In April 2024, an Israeli airstrike on the Iranian consulate in Damascus killed Iranian officers. Iran retaliated with strikes on Israel in April 2024, to which Israel then retaliated with strikes on Iran. In July 2024, Israel assassinated Hamas leader Ismail Haniyeh in Iran's capital Tehran, and then assassinated Hezbollah leader Hassan Nasrallah and prominent IRGC commander Abbas Nilforoushan in Lebanon in September 2024. In October 2024, Iran struck Israel, and Israel struck Iran. The latter Israeli strikes destroyed nearly all of Iran's Russian-supplied defensive S-300 missile systems, paving the way for potential future Israeli strikes.
Israeli prime minister Benjamin Netanyahu cited Iran's nuclear program as the reason Israel preemptively struck Iran. The country developed a covert nuclear weapons program named the AMAD Project in the 1980s and 1990s, which, according to US intelligence assessments, was suspended in 2003.
Iran had consistently said that its nuclear program is solely for peaceful purposes and that it has never intended to develop nuclear weapons. However, since 2019, it had repeatedly violated the terms of the previous nuclear deal of 2015, and in June 2025 the IAEA reported that Iran had acquired enough enriched uranium to produce nine nuclear warheads.
In 2015, six countries negotiated with Iran the Joint Comprehensive Plan of Action nuclear deal to lift sanctions on Iran and freeze Iran's nuclear program. In 2018, after being briefed on evidence that Iran sought to resume its nuclear weapons development, U.S. president Donald Trump unilaterally withdrew from and voided the deal – despite the report by the International Atomic Energy Agency (IAEA) that Iran was keeping to the deal. After the withdrawal Iran began stockpiling enriched uranium, and the IAEA lost the ability to monitor Iran's nuclear facilities.
In a letter addressed to the president of the UN Security Council, the foreign ministers of France, Britain and Germany (E3) stated that since 2019, Iran had "increasingly and deliberately ceased performing its JCPOA commitments", including "the accumulation of a highly enriched uranium stockpile which lacks any credible civilian justification and is unprecedented for a state without a nuclear weapons program," a statement confirmed by the IAEA. The letter detailed additional Iranian violations of the agreement despite the fact that the E3 "have consistently upheld their agreements under the terms of the JCPOA".
In March 2025, US Director of National Intelligence, Tulsi Gabbard, testified that the US intelligence community assessed that "Iran is not building a nuclear weapon". A month later, Trump announced negotiations between the United States and Iran regarding Iran's nuclear program. The White House declared that Iran had two months to secure a deal, which expired the day before Israel's strikes. On 31 May 2025, the IAEA issued a report in which it stated that Iran had enough uranium enriched up to 60% for the production of nine nuclear weapons, and enough for additional weapons at lower enrichment levels.
On 12 June 2025, the IAEA board of governors passed a resolution, drafted by the US, UK, France and Germany, that declared that Iran was non-compliant with its nuclear obligations for the first time since September 2005. IAEA director general Rafael Grossi stated in an interview that the IAEA did "not have any proof of a systematic effort to move into a nuclear weapon", on the other hand, in his statement to the board of governors on 9 June he stated that "Unless and until Iran assists the agency in resolving the outstanding safeguards issues, the Agency will not be in a position to provide assurance that Iran's nuclear programme is exclusively peaceful".