By Jana Winter

WASHINGTON, March 2 (Reuters) - Iran and its proxies could target the U.S. with attacks in response to the Saturday killing of Iranian Supreme Leader Ali Khamenei by Israeli and U.S. strikes, according to a U.S. intelligence assessment reviewed by Reuters.

The February 28 threat assessment produced by the Office of Intelligence and Analysis at the Department of Homeland Security said Iran and its proxies "probably" pose a threat of targeted attacks on the United States, although a large-scale physical attack was unlikely.

With few captains willing to brave the Strait of Hormuz as war rages around the Gulf, companies will have to do business without one of the world's most vital shipping lanes, especially for oil and gas.

- What is the strait's importance to world markets? -

The strait is especially key to the world energy markets, with around 20 percent of global seaborne oil passing through.

By David Brunnstrom

March 2 (Reuters) - U.S. first lady Melania Trump chaired a meeting of the United Nations Security Council on children and education in conflict on Monday, two days after U.S. President Donald Trump and Israel launched attacks on Iran that prompted a U.N. warning about child safety.

It was the first time a spouse of any serving world leader has chaired a meeting of the 15-member Security Council, the U.N. body charged with maintaining international peace and security. The plan was announced last week before the launch of the U.S. and Israeli strikes.

As the sun set in the coastal Israeli city of Tel Aviv on Monday, air raid sirens warning of incoming Iranian missiles sent residents hurrying to shelters just as the Jewish holiday of Purim was starting.

All public gatherings have been banned by military order, but four floors underground in the basement parking lot of a Tel Aviv mall, hundreds of young people gathered in costume, as is customary for the festive holiday -- typically marked by gift-giving and lots of alcohol.

WASHINGTON, March 2 (Reuters) - The United States is not postured for ground forces in Iran at this moment but U.S. President Donald Trump has those options, U.S. Secretary of State Marco Rubio told reporters on Monday, adding that the administration believes that the objective it has set can be achieved without ground forces.

(Reporting by Daphne Psaledakis)

By Lisa Baertlein

LONG BEACH, Calif., March 2 (Reuters) - Container ships account for roughly 100 of the 750 ships backed up around the Strait of Hormuz following U.S. and Israeli attacks on Iran, Jeremy Nixon, CEO of container carrier Ocean Network Express (ONE), said on Monday.

"About 10% of the container ship global fleet is caught up in this," Nixon said at a container shipping industry conference in Long Beach, California.

CAIRO, March 2 (Reuters) - An Iranian Revolutionary Guards senior official said on Monday that the Strait of Hormuz is closed and Iran will fire on any ship trying to pass, Iranian media reported.

This is Iran's most explicit warning since telling ships it was closing the export route on Saturday, a move that threatens to choke a fifth of global oil flows and send crude prices sharply higher.

The United States attacked Iran only after learning that ally Israel was going to strike and fearing Tehran would retaliate against US forces, Secretary of State Marco Rubio said Monday.

"We knew that there was going to be an Israeli action. We knew that that would precipitate an attack against American forces, and we knew that if we didn't preemptively go after them before they launched those attacks, we would suffer higher casualties," Rubio told reporters.

March 2 (Reuters) - Kazakhstan's Foreign Minister discussed events in Iran and throughout the Middle East on Monday with counterparts from Central Asia and Azerbaijan, the Kazakhstan Foreign Ministry said.

A ministry statement said those taking part in the discussion, unusual in that it involved most states in the region at one time, called for a negotiated settlement to the upheaval in and around Iran.

ATHENS, March 2 (Reuters) - Greek police have detained a 36-year-old man on suspicion of spying on a naval base on the island of Crete, a strategic facility for the United States in the eastern Mediterranean, police officials said on Monday.

The man was detained at Athens’ airport on information by the country’s intelligence service.

Souda Bay in Crete is home to military facilities for Greece, the U.S. and the NATO military alliance, and recently, the U.S. aircraft carrier Gerald R. Ford had visited the base for resupply.