The United States and Israel targeted Iran in coordinated attacks over the weekend that killed Supreme Leader Ayatollah Ali Khamenei and dozens of other senior figures and kicked off a furious Iranian response that was expanding into a wider regional war.

Allies of the U.S. pledged to help stop Iran’s missile and drone strikes. The Lebanese militant group Hezbollah claimed strikes on Israel for the first time in more than a year, and Israel fired back.

The first U.S. military deaths have been reported. Other deaths have been confirmed in Israel and Gulf nations, while Iran has said several hundred people have been killed there.

With Khamenei’s death, the Islamic Republic must now choose a supreme leader for the first time since 1989. U.S. President Donald Trump has urged Iranians to seize the moment and overthrow the theocracy that cracked down on nationwide protests early this year. There was no sign that was happening.

Around the world, some protested. Others cheered.

The attacks came two days after the latest U.S.-Iran talks aimed at putting controls on Tehran’s nuclear program. They echoed the events of last year, when talks were cut short by an Israeli attack that led to a 12-day war and U.S. bombing of Iranian nuclear sites. Washington has claimed that Iran was rebuilding its nuclear program in recent months.

Iran has said it hasn’t enriched since June, but it has blocked inspectors with the U.N. nuclear watchdog from visiting the sites America bombed.

Here’s where things stand.

Iran

The 86-year-old Khamenei was killed when his compound was bombed Saturday morning. Iran’s ballistic missile sites, navy headquarters and warships were attacked as well. Iran said strikes also targeted the Natanz nuclear enrichment site. Israel and the U.S. have not acknowledged strikes at the site, though Israel has said it is targeting the “leadership and nuclear infrastructure.”

Khamenei had no designated successor. Iran has set up a three-member leadership council, and Foreign Minister Abbas Araghchi has said a new supreme leader would be chosen in “one or two days.” On the streets, there have been scattered celebrations over Khamenei’s death. Internet restrictions in Iran have complicated efforts to monitor what’s happening.

In retaliation, Iran’s military has struck Israel, where several people have been killed. Iran has also targeted U.S. bases in the region. The U.S. military said four service members were killed, the first known U.S. casualties. Other Iranian strikes have killed a handful of people in Gulf nations including the United Arab Emirates and Kuwait, and hundreds of flights have been affected at some of the world’s busiest airports.

What to watch for: further military strikes, the selection of a new supreme leader, and reactions from the Iranian people.

United States

The strikes came after the U.S. built up its biggest military presence in the region in decades. Israeli and U.S. authorities spent weeks tracking the movements of senior Iranian leaders. Trump has said the “heavy and pinpoint bombing” in Iran would continue through the week or longer.

The U.S. has signaled it is willing to talk to Iran’s new leaders, eventually. Meanwhile, some leaders in Congress have protested at the launch of the strikes without congressional authorization.

What to watch for: further military strikes, effects on U.S. bases and forces, and any diplomacy with Iran’s new leadership.

Israel

Israel sees Iran as an existential threat and has long sought to end its nuclear and ballistic missile programs, while also targeting armed allied groups like Hamas in Gaza and Hezbollah in Lebanon. Israeli attacks have weakened those groups since Hamas’ Oct. 7, 2023, attack on Israel that started the war in Gaza.

Now Israel has pledged “nonstop” strikes and at one point said 100 fighter jets were simultaneously striking targets in Tehran. During last year’s war, Israel pitched Trump a plan to kill Khamenei. Now they have.

Israelis dashed to shelters for safety, but most of Iran’s attacks have been intercepted. Prime Minister Benjamin Netanyahu, under international criticism for the war in Gaza, is claiming a win for Israel’s security.

But risk remains from Iranian-backed groups like the Houthi rebels in Yemen who have vowed to resume attacks on Red Sea shipping routes and on Israel.

What to watch for: further military strikes, as well as attacks by and against Iranian proxies.

The Middle East and beyond

The current conflict is already far more intense than last year’s Israel-Iran war, where the U.S. inserted itself near the end by bombing Iranian nuclear sites and Iran responded with a calculated attack on a U.S. military base in Qatar.

Now, hundreds of Iranian missile and drone strikes have sent people scrambling across Gulf nations that had previously been relatively insulated from the volatility in the region.

The United Arab Emirates said Dubai’s main airport had been affected, and tourists and others flinched at the booms of interceptors. Saudi Arabia said it intercepted attacks, and summoned Iran’s ambassador. Top diplomats of six Gulf states said they had the “right to self-defense.”

Oil prices rose sharply when market trading began Sunday as traders bet that supply from the critical region would slow or stop. Attacks on and near the Strait of Hormuz, the world’s most critical oil chokepoint, are also raising concerns about supply.

In response, eight countries that are part of the OPEC+ oil cartel said they would boost production of crude.

And on Monday, the world was learning the first details about any effects on Iran’s nuclear program as the International Atomic Energy Agency’s Board of Governors met on the conflict.

What to watch for: oil prices, details on Iran’s nuclear program, and diplomatic efforts.