Explained | What to know about the Israel-Iran conflict as the US joins the war

The United States bombed three nuclear sites in Iran, bringing the US military directly into Israel’s war with Iran, a move that could kick off a more dangerous phase in the war.

The attack followed days of uncertainty about whether President Donald Trump would intervene in the conflict, which began with a surprise attack on Iran by Israel on June 13.

Trump said the sites that were hit Sunday morning included Iran’s two major uranium enrichment centers — the under-mountain facility at Fordo and the larger enrichment plant at Natanz. The third site, near the ancient city of Isfahan, is where Iran is believed to keep its near-bomb-grade enriched uranium.

“All planes are now outside of Iran air space,” he said in a social media post Saturday night in the United States, adding that a “full payload” of bombs had been dropped on Fordo. “All planes are safely on their way home.”

Israel has struck Iran’s nuclear facilities in what it says is an effort to stop it from developing a nuclear bomb, though Iran says its nuclear program is peaceful. Ambassadors from Qatar, Saudi Arabia, the United Arab Emirates and Kuwait had earlier expressed concern over the safety of nuclear facilities near their borders, and cautioned that any attack on such sites could have serious consequences.

What’s the latest in Iran?

US warplanes dropped bombs on three nuclear sites in Iran, Trump said.

After a week of mixed signals, Trump, who has long vowed to steer America clear of overseas “forever wars,” authorized US forces to strike Iran’s most heavily fortified nuclear installation, deep underground.

The US bombing early Sunday in Iran followed a wave of airstrikes by Israel on Saturday against missile sites and a nuclear facility in Iran. Israeli forces targeted sites for missile launchers and radars in the Ahvaz region, which would have most likely been on any potential flight path used by US warplanes on the way to strike Fordo.

As the conflict entered its ninth day, Israel also said its strikes had killed three commanders of Iran’s Revolutionary Guard, the most powerful military force in the country.

The civilian toll of the attacks by Israel has steadily risen. Iran’s Health Ministry, in an updated toll of casualties, said Saturday that more than 400 Iranians, including 54 women and children, had been killed since Israel began its attacks, and at least 3,056 others had been wounded. A spokesperson for Iran’s Health Ministry said that most of the casualties were civilians.

Iran’s supreme leader, Ayatollah Ali Khamenei, is taking precautions against assassination, according to three Iranian officials familiar with his emergency war plans. He speaks with his commanders mostly through a trusted aide now, the officials said, and electronic communications have been suspended to make it harder to find him. He has also chosen replacements for his lieutenants down the chain of military command, in case of their deaths. The chief of staff of Iran’s armed forces and senior military commanders have been killed in the conflict.

A near-total internet blackout in Iran appeared to be partially lifted early Saturday, but connectivity collapsed again just two hours later, according to internet monitoring group NetBlocks. The blackout has lasted nearly three days, making it hard for Iranians to communicate with each other or the outside world.

Civilians have borne the brunt of the attacks, as Israeli missiles hit some apartment buildings and residential complexes. Residents who spoke to The New York Times said they had not experienced attacks like this in a generation, with some recalling the Iran-Iraq war of the 1980s.

Israeli airstrikes achieved “direct impacts” on the underground area of the Natanz nuclear site, where Iran enriches uranium, the United Nations’ chief nuclear monitor said Tuesday, based on new satellite images. That indicates more serious damage than previous assessments of the attack had shown.

What’s the latest in Israel?

On Saturday, Iran fired a barrage of ballistic missiles and launched drones into Israel. The drones set off air raid sirens in northern Israel and the Israeli-controlled Golan Heights. Over the last week, Israel has generally intercepted Iranian drones, which travel relatively slowly, with no reports of casualties.

On Friday, missiles from Iran damaged buildings in the southern Israeli city of Beersheba and in downtown Haifa, Israel’s third-largest city.

The Israeli military said that Iran had launched a missile with a cluster munition warhead at a populated area in central Israel on Thursday, according to Lt. Col. Nadav Shoshani, a military spokesperson. It is the first report of that type of weapon being used in the current war.

Iran’s mission to the United Nations declined to respond to the Israeli claim, which was linked to a ballistic missile that struck Or Yehuda, Israel, and nearby towns. No one was killed by the missile or its bomblets; it was unclear if anyone was injured.

Israel has invested billions of dollars in sophisticated and multilayered aerial defenses, but they are now being put to the test.

Since Iran started retaliating against Israel’s fire last week, Israel’s world-leading air defense system has intercepted most incoming Iranian ballistic missiles, giving the Israeli air force more time to strike Iran without incurring major losses at home.

As the war continues, Israel is firing interceptors faster than it can produce them.

How has the United States joined the conflict?

For days, Trump had been weighing whether to provide Israel the powerful munitions needed to destroy Iran’s deeply buried nuclear enrichment facilities at Fordo. Only the US military has the 30,000-pound bombs known as bunker busters that are believed up to the job, and only American aircraft can deliver them.

Just days ago, the Trump administration appeared intent on distancing itself from the conflict. “We are not involved in strikes against Iran, and our top priority is protecting American forces in the region,” Secretary of State Marco Rubio declared.

But Trump, when he was not urging peace talks, began sounding increasingly belligerent.

Experts expected that direct participation of the US military in Israel’s bombing campaign would lead to a quick retaliation from Iran against US troops stationed across the Middle East.

What is the Massive Ordnance Penetrator?

The US Air Force developed the Massive Ordnance Penetrator, or GBU-57, to penetrate underground defenses. It is also called a bunker buster.

The United States began designing the weapon in 2004, during the George W. Bush administration, specifically to attack nuclear facilities constructed deep beneath mountains in Iran and North Korea. It was tested and added to the US arsenal during Trump’s first term.

The bomb has a much thicker steel case and contains a smaller amount of explosives than similarly sized general-purpose bombs. The heavy casings allow the munition to stay intact as it punches through soil, rock or concrete before detonating.

Its size and weight — 20 feet long and 30,000 pounds — means that only the American B-2 stealth bomber can carry it. While Israel has fighter jets, it has not developed heavy bombers capable of carrying the weapon.

The US military has concluded that one bomb would not destroy the Fordo facility on its own; an attack would have to come in waves, with B-2s releasing one bomb after another down the same hole.