By Samia Nakhoul, Parisa Hafezi and Emily Rose

DUBAI, March 1 (Reuters) - The assassination of Iran's Supreme Leader Ayatollah Ali Khamenei has plunged the Islamic Republic into its most perilous crisis since the 1979 revolution - confronting it with war on its own territory, an unresolved succession, and mounting internal strain.

DUBAI, March 1 (Reuters) - Israeli strikes hit a hospital in Tehran’s Gandhi Street area, two witnesses told Reuters on Sunday, saying the hospital was badly damaged and patients were being taken out.

(Reporting by Parisa HafeziEditing by Peter Graff)

By Doina Chiacu

March 1 (Reuters) - The United States has yet to spell out a "day-after" strategy for Iran following joint U.S.-Israeli strikes that killed much of the country's leadership, lawmakers from both major political parties said on Sunday.

Ilana Malka doesn't know if her three great-nephews are alive after an Iranian missile struck a shelter in her city of Beit Shemesh, in central Israel, leaving a crater in the ground and a void in the community.

The building that housed the shelter was blown to bits by the hit, sending chunks of concrete large enough to destroy cars 50 metres (yards) away.

The missile hit the public protection centre while its door was still open to allow people in, Malka and other residents said, killing at least 9, injuring 46, and leaving 11 missing, according to the police.

At least 17 people were killed Sunday across Pakistan as protesters outraged over the death of Iran's supreme leader took to the streets, with some attempting to storm US diplomatic buildings.

In the Pakistani megacity of Karachi, an AFP journalist witnessed hundreds of pro-Iranian protesters trying to enter the US consulate, prompting clashes with police.

At least 10 people had died and over 70 were injured as of Sunday evening, the office of the Karachi police surgeon said.

Earlier, a hospital toll seen by AFP listed nine people as having died from gunshot wounds.

The killing of Iran's supreme leader Ayatollah Ali Khamenei and the ongoing US-Israeli bombing campaign have ushered in a period of uncertainty for the country's leadership.

At the beginning of the air campaign, US President Donald Trump urged Iranians to seize power once it was over, having voiced support for mass protests against the clerical leadership that peaked in January before a deadly crackdown.

- Continuity for now -

By Phil Stewart and Idrees Ali

WASHINGTON, March 1 (Reuters) - U.S. President Donald Trump announced on Sunday that the U.S. military was sinking Iran's Navy, having destroyed nine Iranian warships so far and "going after the rest."

Trump made the announcement in a social media post as the Pentagon intensified its bombings of Iran's military, deploying B-2 stealth bombers from the U.S. to strike at hardened, underground Iranian missile facilities with 2,000-lb bombs.

U.S. strikes also pummeled Iran's naval headquarters, largely destroying it, Trump said.

ATHENS, March 1 (Reuters) - More than a thousand demonstrators marched to the U.S. and Israeli embassies in Athens on Sunday to protest against strikes in Iran.

Demonstrators mainly affiliated to the Greek Communist Party held banners and placards reading "Hands off Iran" and "close Souda base".

Greece on Saturday tightened security in Souda naval base on the island of Crete, a strategic facility for the United States in the eastern Mediterranean.

The U.S. and Israeli embassies were cordoned off with rows of blue police buses.

BERLIN, March 1 (Reuters) - Israel has flown its official government aircraft to Germany and parked it for safety at Berlin's airport, German government sources said, after U.S. and Israeli strikes killed Iranian Supreme Leader Ayatollah Ali Khamenei and plunged the region into conflict.

Media reports citing data from the Flightradar24 flight tracking service said the aircraft departed Israel early on Saturday afternoon and circled over the Mediterranean before flying to Germany in the evening.

The biggest disruption to global air transport since the Covid pandemic snarled travel for a second day on Sunday, with thousands of flights affected and busy Gulf hubs including Dubai and Doha shuttered as Iran lashed out after US-Israeli strikes.

Passengers were stranded around the world as airlines sought to reroute around the Middle East, where most countries had slammed their airspace shut as Iran launched retaliatory strikes on the glittering Gulf cities.