The AUSMIN meeting will have a wide-ranging agenda, and will include the pressing security issues of the day, not least the situation in Iraq.
And analysts say there's likely to be steps towards an even closer military relationship between the two countries, to expand the US Marines rotation in the Northern Territory to include the US Navy and Air Force.
Reporter: Lexi Metherell
Speakers: Bates Gill, chief executive of US Studies Centre; Chuck Hagel, US secretary of defence; Rory Medcalf, Lowy's international security program
LEXI METHERELL: The AUSMIN agenda is loaded with important matters, including tensions with Russia, China's activities in the region's oceans and the threat of the Islamic State in Iraq.
The US is now carrying out air strikes in Iraq and the Defence Minister David Johnston has not ruled out providing military support.
But the chief executive of US Studies Centre, Bates Gill, says the US is unlikely to request military help in the near-term.
BATES GILL: Given that the United States itself is moving in very cautious ways and trying to really weigh carefully how to deal with this emerging challenge in Iraq, I suspect that it would likewise be very reluctant and careful and cautious about asking friends and allies to join in on this.
LEXI METHERELL: Amidst the pressing security issues, there'll be something of a milestone for the alliance.
The AUSMIN leaders will sign the Force Posture Agreement, or FPA, which will provide the legal framework for US troops in Darwin.
The US secretary of defence, Chuck Hagel.
CHUCK HAGEL: The rotational presence, for example, of US Marines in Darwin and American airmen in northern Australia is a good example of what the FPA will allow us to do as we work more closely together in new ways.
LEXI METHERELL: Such new ways of co-operation are likely to include increased access to Australian facilities by not just US marines, but the US Navy and Air Force as well
AUSMIN leaders will today consider a study on options for placing US Navy vessels in Western Australia.
BATES GILL: We should expect going forward that there would be some increased American access on a rotational basis. So in other words, only some portions of the year, some access by American forces, naval ships, air craft, especially in the northern part of Australia.
LEXI METHERELL: The US Studies Centre and the Lowy Institute hosted a pre-AUSMIN discussion with the secretary Hagel and Senator David Johnston yesterday.
The director of the Lowy's international security program, Rory Medcalf, says Australia won't rush into anything.
RORY MEDCALF: I think it's fair to speculate that the Government will be mindful of the need to sell an understanding to the public and to really insure that the public understands what the alliance is for in a changing Asia.
So I don't think we'll see radical steps in American force posture in Australia this year, but I do think we'll see the beginning of conversations about access to naval facilities, access to air facilities. And of course next year, after the Australian Government has completed and issued its next defence white paper, I think then we're likely to see an AUSMIN- a meeting between Australian and the United States that really begins to take some of these ideas forward.