Cameron Stewart writes in The Australian today about the announcement by the US Chief of Naval Operations (from his Navigation Plan 2014-2018) that he aims to 'provide amphibious lift for US marines operating out of Australia by establishing a fifth amphibious readiness group in the Pacific by financial year 2018'.

The US Navy already has one amphibious ready group (ARG) and a carrier strike group based in Japan with the 7th Fleet. But an additional ARG in our region would allow better crisis response in the maritime crossroads of South East Asia, and possibly into the eastern Indian Ocean. The US Marine Corps plans to build a rotational presence for a full Marine Air Ground Task Force (a force of 2500 Marines with armoured vehicles and aircraft) in Darwin in the coming years. It makes a lot of sense that it would need amphibious vessels with which to deploy.

There are three possibilities for where these vessels could come from. The first option is that the US could build additional amphibious assault ships like the soon-to-be commissioned USS America, but at US$3.6 billion per ship this seems unlikely during sequestration.The second option would be to relocate ships to the Pacific from an existing homeport on the US east coast, but domestic political pressures make this unlikely; just moving an ARG from Virginia to Florida has been a vexed task.

The third option, and the most likely, is that the US Navy will experiment with new and cheaper amphibious ships for its new Pacific ARG.

In a speech in Singapore in May this year, Admiral Greenert pointed to a mix of Littoral Combat Ships, Joint High Speed Vessels (pictured), and a newer amphibious ship concept termed the 'Afloat Forward Staging Base' which is 'something that's perhaps better suited for this region, and its balance and capabilities that we bring to this region'. These US Marine Corps briefing slides show current thinking about how the new concept might work.

Admiral Greenert makes clear that, besides four Singapore-based littoral combat ships, which could form part of the ARG, the US Navy is looking to bring another three to the region by 2020. They will be joined by three Joint High Speed Vessels and a new experimental ship called the USNS Montford Point which will be based in Guam 'in a few years'. This last ship is essentially a modified commercial oil tanker from which landing craft and helicopters can operate. The key advantage of using this ship? Cost. About 20-25% of the expense of building a more conventional amphibious assault ship like USS America.

So where will this new ARG be based? Admiral Greenert addressed this during a CSIS conference on the future of maritime forces in July:

And that will expand itself until we have a MEU-size force operating out of Darwin, deployed out of Darwin, where we will have an ARG MEU-sized capability by the end of this decade.

But though the ARG may have a forward presence in Darwin, there would be a lot of problems associated with basing US amphibious ships in Darwin Harbour permanently, and it is more likely that the new ARG will operate primarily from Guam. Certainly current construction works on Guam envisage the regular presence of an ARG.

US and Australian political leaders are still talking about 'places' rather than bases for the US Marine Corps in Darwin. The US Marine Corps, however, is further out in front, referring to future 'bases' in Australia for the III Marine Expeditionary Force in this recent document (p.13). But during the election campaign, the Australian Defence Department is playing it safe. Its comment on this morning's story: 'The positioning of US Navy assets is a matter for the US government.'