By Alexander Cornwell, Jana Choukeir and Trevor Hunnicutt, Reuters

US President Donald Trump has assailed NATO allies over their lack of support for the US-Israel war against Iran.
Photo: ALEX WONG / Getty Images via AFP

The United States military is deploying a large amphibious assault ship with thousands of additional Marines and sailors to the Middle East, three US officials told Reuters, as Iran's new supreme leader hailed Iran's "unity" and "resistance".

Reuters had reported that Washington, desperate to reopen the Gulf oil bottleneck of the Strait of Hormuz, shut by Iran since the US and Israel attacked almost three weeks ago, was considering deployments up to and including landings.

Oil prices have risen around 50 percent since the start of the war.

The news came shortly after President Donald Trump again vented his fury at US allies for declining to help open the strait while fighting continued, albeit in a conflict they were neither consulted on nor advised of.

The sources, speaking on condition of anonymity, did not say what the role of the additional troops would be.

As Muslims around the region tried to celebrate Eid al-Fitr, which ends the fasting month of Ramadan, and Iranians marked Nowruz, the Persian New Year, the prospect of a quick end to a war about to enter its fourth week seemed remote.

Mujtaba Khamenei, Iran's new supreme leader, who has not been seen in public since the Israeli attack that killed his father and predecessor on the war's first day, posted a Nowruz message on his Telegram channel.

"The enemy believed that by targeting the leader (Ayatollah Ali Khamenei) and influential figures, it could instil fear and force the people to withdraw," it said.