A joint military strike by the U.S. and Israel on Iran has entered its third day. Expanding military operations by the U.S. and Israel, as well as retaliatory strikes from Iran, have escalated the situation into a regional conflict encompassing Gulf nations.

The following is a timeline of the escalating situation since the start of the conflict.

February 28

06:20 GMT

Explosions reported in the Iranian capital, Tehran.

06:30 GMT

Israel's Defense Minister Israel Katz confirmed a "preemptive" strike on Iran, declaring a nationwide state of emergency. Air raid sirens sounded across Israel, with emergency alerts sent to civilians.

Fars, an Iranian semi-official news agency, reported multiple missile strikes in central Tehran, with additional explosions in Isfahan, Qom, and Kermanshah. Reports also suggested strikes targeted the office of Iran's Supreme Leader Ali Khamenei.

07:00 GMT

Iran and Israel closed their airspace. Israel and the U.S. declared negotiations with Iran no longer viable. U.S. Central Command (CENTCOM) said the U.S. military campaign, named Operation Epic Fury, is focused on dismantling Iran's security apparatus, prioritizing locations that posed an imminent threat.

07:30 GMT

U.S. President Donald Trump released a statement at the Mar-a-Lago resort in Florida, announcing that the U.S. military had launched a "major military operation" in Iran and vowing to destroy Iran's missile industry, naval forces, and nuclear capabilities.

Around 08:00 GMT

Iranian media said the country's military was preparing a "crushing response." Israel reported detecting the launch of Iranian missiles.

Around 08:30 GMT

More explosions were heard in Tehran. The Islamic Revolutionary Guard Corps (IRGC) announced large-scale missile and drone attacks.

08:40 GMT

Israel claimed to have detected a second barrage of missiles launched from Iran.

09:00 GMT

There would be "no red lines" for Iran's retaliation, according to an Iranian official.

Explosions were reported across Israel, with damage reported in the northern city of Haifa.

09:30 GMT

Iranian media reported strikes on U.S. military bases across the region. Explosions were reported in Bahrain, the United Arab Emirates, Qatar, Saudi Arabia, Kuwait and Jordan.

Reports indicated the U.S. Fifth Fleet service center in Bahrain was struck by an Iranian missile.

11:00 GMT

Iranian media reported that a deadly strike hit a girls' elementary school in southern Iran. The death toll from the attack had risen to 165 on Sunday, according to Iran's official IRNA news agency. Iranian officials said most of the victims were schoolchildren.

12:00 GMT

The IRGC claimed it destroyed a U.S. radar installation in Qatar.

15:00 GMT

The Israeli military said it had carried out large-scale strikes on Iran's air defense systems, significantly degrading them.

19:40 GMT

The Iranian Red Crescent reported that strikes across 24 provinces killed 201 people, with 747 injured.

March 1

01:30 GMT

Iranian media confirmed the country's supreme leader, Ali Khamenei, had been killed. The government declared 40 days of national mourning.

2:30 GMT

CBS reported that around 40 Iranian officials were killed in the Israeli-U.S. strike, including Defense Minister Aziz Nasirzadeh and IRGC commander Mohammad Pakpour.

Around 15:00 GMT

In an interview with Al Jazeera, Iran's Foreign Minister Abbas Araghchi suggested that Iran's military units were acting independently, saying that striking Oman was not a decision made by the country's leadership.

05:30 GMT

Mohammad Bagher Ghalibaf, Iran's parliament speaker, said Iran had prepared a contingency plan for the post-Khamenei period.

06:00 GMT

Ali Larijani, secretary of Iran's Supreme National Security Council, said an interim leadership would be formed and a new supreme leader selected.

14:50 GMT

The IRGC claimed it launched four ballistic missiles at the U.S. carrier USS Abraham Lincoln. The U.S. denied Iran's missiles hit its aircraft carrier. CENTCOM later announced the killing of three U.S. troops, but without specifying when and where the death occurred. This marks the first U.S. casualties in the military operation against Iran.

17:00 GMT

The IRGC said it struck three oil tankers belonging to the United States and Britain in the Gulf and the Strait of Hormuz, with the vessels reported on fire, according to its official outlet Sepah News.

21:40 GMT

Trump said in a video statement that the combat operation would continue until "all of our objectives are achieved." Regarding the three killed U.S. troops, Trump said "there will likely be more" before the conflict ends.

Trump also claimed the U.S. strike largely destroyed Iran's naval headquarters and sank nine Iranian naval ships. The U.S. would continue to destroy the remaining Iranian warships, he said.

March 2

01:10 GMT

The Israeli military said it has begun striking the Iran-backed militant group Hezbollah across Lebanon. 

Hezbollah claimed an earlier attack targeted an Israeli military missile defense facility in Haifa in retaliation for the killing of Iran's supreme leader, Ali Khamenei, and for repeated Israeli aggressions, according to a statement.

Around 05:30 GMT

Multiple Middle East news outlets reported that an F-15 fighter jet crashed over Kuwait, with both pilots ejecting safely. Iran claimed it shot down the jet.

06:00 GMT

According to the Lebanese Ministry of Health, an Israeli airstrike killed at least 31 people and injured 149 on Monday.

(With inputs from agencies)