POTENTIALLY thousands of extra American sailors and Marines will flood through the Darwin port in coming years with a US General confirming a greater military presence in the South Pacific.

The head of US Marine Corps Force Command, Lieutenant General John Wissler, said the Pentagon planned to dispatch another three-ship amphibious ready group to the Asia-Pacific region as early as October 2018.

The Marine Corps Times reported that the ships would likely carry an embarked Marine Expeditionary Unit (MEU).

That would see an extra 4000 sailors and Marines in the region.

Lt-Gen Wissler said the goal of the MEU was to augment the number of Marines already coming to the Top End as part of the annual six-month Marine Rotational Force Darwin deployment.

This year, about 1250 Marine are deployed to Darwin, based mostly at Robertson Barracks about 20km from the Darwin CBD.

US and Australian officials hope to boost that number to 2500 by 2020.

“The actual basing (of the extra Marines and sailors) ... and all of those significant details are being worked out,” Lt-Gen Wissler said.

“That’s why it’s a (fiscal) 2019 problem because, as you can imagine, it’s a very complex undertaking.”

The Japan-based 31st Marine Expeditionary Unit presently conducts two 90-day patrols in the Pacific each year — one in spring and another in autumn — and respond to humanitarian crises in the region throughout the year.

Lt-Gen Wissler said the new arrangement would allow that unit to focus on north eastern Asia while the new ARG/MEU conducted two 90-day patrols in the South Pacific.

He said the Marine Corps has not determined whether the new MEU will come from the continental US, Hawaii or Japan.

Lieutenant Commander Matt Knight from the US Pacific Fleet said it is too soon to say which ships may be assigned to the MEU in fiscal 2019.

Former Chief of Naval Operations Admiral Jon Greenert said the amphibious assault ship America was a “prime candidate” to visit Australia as part of such a group.

“They will go into Darwin … and conduct on-load and off-load,” he told Navy Times in March 2015.

He said while the Marines trained in the Top End of Australia, the ships in the ARG could operate and hold exercises in South East Asia.