A US military ship is sailing towards the Middle East, carrying equipment to build a temporary pier off the coast of Gaza, the army says.
The support ship, General Frank S Besson, set sail from a military base in the state of Virginia on Saturday.
It comes after President Joe Biden said the US would build the floating harbour to help get aid into Gaza by sea.
The UN has warned that famine in the Gaza Strip is “almost inevitable” and children are starving to death.
Aid deliveries by land and air have proved difficult and dangerous.
The World Food Programme had to pause land deliveries after its convoys came under gunfire and looting. And on Friday, there were reports that five people had been killed by a falling aid package, when its parachute failed to open properly.
The US ship departed “less than 36 hours” after Mr Biden made his announcement, US Central Command wrote on X.
It is “carrying the first equipment to establish a temporary pier to deliver vital humanitarian supplies” to Gaza, the statement continued.
The Pentagon has said it could take up to 60 days to build the pier with the help of 1,000 troops – none of whom would go ashore.
Charities have said those suffering in Gaza cannot wait that long.
Meanwhile, an aid ship laden with some 200 tonnes of food was still waiting for clearance to set sail from a port in Cyprus on Sunday morning.
It is hoped the vessel, Open Arms, will be able to depart before Monday, following an EU announcement that a new sea route would be opened over the weekend to allow aid to sail directly from Cyprus – the closest EU country to Gaza.
The ship belongs to the Spanish charity of the same name, Open Arms, and the food on board has been provided by US charity World Central Kitchen.
It is unclear how any aid delivered by sea would get safely to shore before the US pier is built. Gaza has no functioning port and its surrounding waters are too shallow for large vessels.
However Oscar Camps, the founder of Open Arms, told the Associated Press that at the destination point – which remains a secret – a team from the World Central Kitchen has been building a pier to receive the aid.
Israel has welcomed the ocean initiative, and said aid would be delivered after security checks were carried out in Cyprus “in accordance with Israeli standards”.
Israel’s military launched an air and ground campaign in the Gaza Strip after Hamas’s attacks on Israel on 7 October, in which about 1,200 people were killed and 253 others were taken hostage.
More than 30,900 people have been killed in Gaza since then, the territory’s Hamas-run health ministry says.