US Navy Helicopter Crashes in Arabian Sea, One Service Member Missing

A US Navy service member is missing and three others have been injured after their twin-engine helicopter went down in the Arabian Sea, according to military central command authorities.

The MH-60S Sea Hawk chopper, which was assigned to the USS George H W Bush Nimitz-class aircraft carrier, made an "emergency landing" on Wednesday, local time, a military statement said.

"There is no indication the emergency was caused by hostile action," the US Naval Forces Central Command said.

"Three of the helicopter's four crew members have been recovered and are in stable condition aboard George H W Bush.

"US Navy assets in the region are currently searching for other aircrew men still missing. The cause of incident is under investigation."

The USS George H W Bush is one of two aircraft carriers that continue to operate in the Middle East, US Central Command said on June 24.

Helicopter water landings can be dangerous, even for experienced pilots, given the propensity of top-heavy aircraft to flip upside-down during submersion.

American forces in the region are also on high alert amid periodic flare-ups in violence during the ceasefire between the US and Iran.

The US and Iran have agreed to stand down on strikes and vessels are allowed to move freely in the region, after the signing of a memorandum of understanding (MOU) in a bid to end the war.

The talks include arrangements around the Strait of Hormuz, the removal of a US blockade on Iranian ports and sanctions on Iran, and the future of Iran's stockpile of highly enriched uranium.

The two sides have 60 days from their signing of the memorandum of understanding earlier this month to work out details.

The incident is the latest in a series of similar recent aircraft incidents that have unfolded during US operations in the Middle East amid the ongoing war in Iran.

US President Donald Trump last month confirmed a US Army AH-64 Apache attack helicopter also went down near the Strait of Hormuz, but the chopper's pilots were not injured.

A US Navy drone boat was deployed after the helicopter went down as part of a maritime rescue mission to recover the pilots, who were floating at the crash site for up to two hours.

In April, US forces also pulled off a daring rescue of two aviators who ejected from their F-15E Strike Eagle fighter jet after being shot by Iranian fire.

One of the airmen hid in a mountain crevice while US military forces worked to rescue him, while his colleague needed to be retrieved from behind enemy lines under the cover of darkness.