At least three tankers were damaged off the Gulf coast and one seafarer was killed as Iranian retaliation for U.S. and Israeli strikes on Iran exposed ships to collateral damage, shipping sources and officials said on Sunday.

Risks to commercial shipping have surged in the past 24 hours, with more than 200 vessels including oil and liquefied gas tankers dropping anchor around the Strait of Hormuz and surrounding waters, shipping data showed on Sunday.

Iran has said it has closed navigation through the critical waterway, prompting Asian governments and refiners - key buyers - to assess oil stockpiles.

The U.S. military announced on Sunday the first American casualties, as a new poll showed only one in four Americans supported strikes against the Middle Eastern country.

As the conflict entered its second day, Trump said 48 Iranian leaders had been killed and that the U.S. military had started sinking Iran's Navy, destroying nine Iranian warships so far and "going after the rest."

U.S. aircraft and warships have struck more than 1,000 Iranian targets since Trump ordered the start to major combat operations on Saturday, the U.S. military said. The strikes include B-2 stealth bombers dropping 2,000-lb bombs on hardened, underground Iranian missile facilities.

Major container shipping lines have rerouted round the Cape of Good Hope.

"The U.S.-Israeli attack on Iran dramatically increases the security risk to ships operating in the Persian Gulf and adjacent waters," said Jakob Larsen, chief safety and security officer at shipping association BIMCO.

It was not immediately clear who launched the projectiles and drones that targeted or damaged ships on Sunday.

U.S. President Donald Trump said meanwhile that the United States had destroyed nine Iranian navy ships and pummeled Iran's naval headquarters.

'SHIPS MAY BE TARGETED DELIBERATELY OR IN ERROR'

"Ships with business connections to U.S. or Israeli interests are more likely to be targeted, but other ships may also be targeted deliberately or in error," BIMCO's Larsen said.

A projectile hit the Marshall Islands–flagged product tanker MKD VYOM, killing a crew member on board as the vessel sailed off the coast of Oman, vessel manager V.Ships said on Sunday.

"The vessel suffered an explosion and subsequent fire after being struck," V.Ships Asia said in a statement.

"It is with great sadness that we confirm one crew member, who was in the engine room at the time of the incident, has died," the statement said.

The IMO urged companies to avoid sailing through the affected area until conditions improved.

A oil tanker under U.S. sanctions was also hit on Sunday off Oman's Musandam peninsula, injuring four people, the country's maritime security centre said without specifying what hit the vessel.

Another tanker in the UAE port of Jebel Ali was almost damaged by falling debris from an aerial interception after overnight Iranian attacks targeting Gulf states, maritime security sources said.

A third, oil-bunkering tanker was damaged off the UAE coast, two shipping sources said.

A fourth vessel, an oil products tanker, was targeted with a drone off the coast of the UAE, although it managed to sail without being damaged, maritime security sources said.

Port operations at Jebel Ali have been paused due to the situation, officials said on Sunday.

RISK OF MINES

Vessels were advised to keep clear of the Strait of Hormuz and wider Gulf of Oman because of the risk of retaliatory strikes by Iran, the U.S. transport ministry's Maritime Administration said separately in a note on Saturday.

"Any U.S.-flagged, owned or crewed commercial vessels that are operating in these areas should maintain a standoff of 30 nautical miles from U.S. military vessels to reduce the risk of being mistaken as a threat," it said.

There was also the potential risk of mines being laid by Iranian forces in the narrow lanes within the Strait of Hormuz, security sources said.

The Iranian military loaded naval mines on vessels in the Persian Gulf in June, heightening concern in Washington that Tehran was gearing up to establish a Strait of Hormuz blockade, two U.S. officials told Reuters in July.

Maritime sources said they expected war risk insurance rates to surge when underwriters reviewed cover on Monday.

War risk cover is required when sailing into perilous areas and the Lloyd's of London market has already listed Iran, the Gulf and parts of the Gulf of Oman as high-risk.

"We would estimate that near-term rate increases for marine hull insurance in the Gulf could range from 25% to 50%," said Dylan Mortimer at insurance broker Marsh.

NATO RESPONSE

The European Union's naval mission Aspides for the Red Sea, Gulf and Indian Ocean will be reinforced with additional ships, the bloc's foreign policy chief Kaja Kallas said on Sunday.

"Our naval mission, Aspides, has seen a sharp rise in protection requests, and we will reinforce it with additional ships to bolster maritime security in the region," Kallas said in a statement after a videoconference with European foreign ministers, adding that she also plans to convene a meeting with Gulf countries.

(Reuters)