Israel and Iran opened a new chapter in their prolonged history of conflict when Israel initiated a significant attack with strikes early Friday, triggering explosions in Tehran, the capital of Iran.

According to Israel, the operation targeted nuclear and military sites. Meanwhile, Iranian state media reported the deaths of the leader of the paramilitary Revolutionary Guard along with two prominent nuclear scientists.

Israel’s attack comes as tensions have escalated over Iran’s rapidly advancing nuclear program, which Israel sees as a threat to its existence.

Here is a timeline of some significant events in the hostilities between the two countries:

Iran’s nuclear program is a primary target

In 2010, the Stuxnet computer virus was uncovered and is widely considered to be a collaborative U.S.-Israeli effort. The virus caused disruption and destruction to Iranian centrifuges.

2018 — Prime Minister Benjamin Netanyahu says Israel obtained tens of thousands of pages of data showing Iran covered up its nuclear program before signing a deal with world powers in 2015. An ex-Mossad chief confirms the information was obtained by more than a dozen non-Israeli agents from safes in Tehran in 2018.

2020 — Alleged Israeli attacks against Iran’s nuclear program are stepped up significantly after the disintegration of the 2015 nuclear deal meant to keep Iran from developing nuclear weapons.

July 2020 — A mysterious explosion tears apart a centrifuge production plant at Iran’s Natanz nuclear enrichment facility. Iran blames the attack on Israel.

November 2020 — A top Iranian military nuclear scientist, Mohsen Fakhrizadeh, is killed by a remote-controlled machine gun while traveling in a car outside Tehran. A top Iranian security official accuses Israel of using “electronic devices” to remotely kill the scientist, who founded Iran’s military nuclear program in the 2000s.

April 11, 2021 — An attack targets Iran’s underground nuclear facility in Natanz. Iran blames Israel, which does not claim responsibility, but Israeli media widely reports the government orchestrated a cyberattack that caused a blackout at the facility.

April 16, 2021 — Iran begins enriching uranium up to 60%, its highest purity ever and a technical step from weapons-grade levels of 90%.

June 2022 — Iran accuses Israel of poisoning two nuclear scientists in different cities within three days of each other, though circumstances remained unclear.

Mideast wars

Oct. 7, 2023 — Hamas militants from the Gaza Strip storm into Israel, killing 1,200 people and taking 250 hostage, beginning the most intense war between Israel and Hamas. Iran, which has armed Hamas, offers support to the militants.

Feb. 14, 2024 — An Israeli sabotage attack causes multiple explosions on an Iranian natural gas pipeline running from Iran’s western Chaharmahal and Bakhtiari province to cities on the Caspian Sea.

April 1, 2024 — An Israeli airstrike demolishes Iran’s Consulate in Damascus, Syria, killing 16 people including two Iranian generals.

April 14, 2024 — Iran launches an unprecedented missile and drone attack on Israel, firing over 300 missiles and attack drones in response to the Israeli airstrike in Damascus. Working with a U.S.-led international coalition, Israel intercepts much of the incoming fire.

April 19, 2024 — A suspected Israeli strike hits an air defense system near an airport in Isfahan, Iran.

July 31, 2024 — Hamas leader Ismail Haniyeh is assassinated by an apparent Israeli airstrike during a visit to Tehran. Israel had pledged to kill Haniyeh and other Hamas leaders over the Oct. 7 attack.

Sept. 27, 2024 — Israeli airstrike kills Hezbollah leader Hassan Nasrallah. Formed by Iranian Revolutionary Guard members who went to Lebanon in 1982 to fight invading Israeli forces, Hezbollah was the first group that Iran backed and used as a way to export its brand of political Islam.

Oct. 1, 2024 — Iran launches its second direct attack on Israel, though a U.S.-led coalition and Israel shoot down most of the missiles.

Oct. 16, 2024 — Israel kills Hamas leader Yahya Sinwar in the Gaza Strip.

Oct. 26, 2024 — Israel openly attacks Iran for the first time, striking air defense systems and sites associated with its missile program.

April 30, 2025 — Iran executes a man it said worked for Israel’s Mossad foreign intelligence agency and played a role in the killing of Revolutionary Guard Col. Hassan Sayyad Khodaei in Tehran on May 22, 2022.