This morning Prime Minister Tony Abbott and US President Barack Obama announced the conclusion of a series of agreements between the US and Australia. Chief among these is the US–Australia Force Posture Agreement. It details arrangements for the enhanced military cooperation measures first announced when Obama visited Australia in November 2011.

The agreement has taken longer than anticipated, largely because neither side has wanted to pick up the bill for the new defence facilities required in northern Australia. That issue appears to have been resolved, and the US President made a point of acknowledging the Prime Minister's recent commitment to rectifying shortfalls in Australian defence funding. The force posture agreement formalises existing plans to increase the rotation of US Marine Corps troops through Darwin, and to embark on trilateral military exercises in Southeast Asia. But it also the lays the foundation for new alliance defence initiatives, not least of which is a deepening Australian involvement in ballistic missile defence.

Though it wasn't seized on by media traveling with the Prime Minister, this US statement says that 'We are also working to explore opportunities to expand cooperation on ballistic missile defense, including working together to identify potential Australian contributions to ballistic missile defense in the Asia-Pacific region.'

Though BMD cooperation was mentioned in the last government's Defence White Paper, it's likely to accelerate under the Coalition government. This might mean the Australian Defence Force (ADF) could end up mounting advanced missiles on its Aegis-equipped air warfare destroyers, forming part of a US network in Asia equipped to shoot down hostile missiles. This cooperation is largely designed to guard against an increasingly belligerent North Korea, but will be watched keenly by China.

US Marine Corps rotations through Darwin will continue on their current trajectory, building to a full contingent of 2500 in 2-3 years. It is likely that the US Army will preposition military equipment and stores in Darwin too so it can respond more quickly to a crisis in South East Asia. Trilateral military exercises between the Marine Rotational Force-Darwin, the ADF, and either Indonesia or China have been mooted for some time and can now be realised.

US Air Force rotations through northern Australia should increase, assuming the force posture agreement clears the way for the expansion of runways and ramp space at RAAF Learmonth and RAAF Tindal. Australians should expect to see more USAF long-range bombers, transport aircraft, and air-to-air refuelers operating from those locations. There may have been a decision on the suitability of upgrading airfields at Australia's Cocos Island territory to support P-8 maritime surveillance operations too, as foreshadowed in the 2012 Australian Defence Force Posture report. These initiatives will deepen the US military's ability to mount operations from Australia, referred to by the White House as an 'anchor of peace and stability in the Asia-Pacific region and beyond'.

The announcements this morning also discuss strengthened space cooperation between the US and Australia. The US has already agreed to relocate a C band space surveillance radar to Exmouth in Western Australia as well as the establishment of a space telescope to classify and track objects in orbit. The next step would be the establishment of an Australian station as part of the US Space Fence program. In this promotional video from Lockheed Martin* a site for an S band surveillance radar is identified in Western Australia. This month the US Department of Defense awarded a US$914 million contract to build the first station in this program on Kwajalein Atoll in the Marshall Islands. The second station in Australia could be operational by 2021, affording the US better geographic coverage of what is taking place in space. Space-based operations are becoming a critical area of cooperation between the US and Australia – Australia's geography offers unique advantages, underpinned by the skills of scientists in CSIRO and DSTO.

A detailed public conversation is now needed on what access the US military might have to naval facilities in Western Australia. Options ranging from increased US Navy ship visits to the hosting of US submarines, aircraft carriers, and amphibious groups have been mooted. This 2012 CSIS study outlines some of the options being considered.

A US presence in the Royal Australian Navy's Fleet Base West has also been discussed in detail during recent US congressional hearings. But Australian officials have thus far been coy with the public about where these conversations are headed. That's unnecessary; as the 2014 Lowy Institute Poll shows, support for the US alliance remains remarkably high. By not having a public conversation about the future posture of the US Navy on Australia's west coast, the Government cedes the ground to critics who argue that the US alliance should be done away with. This year's Defence White Paper process allows an opportunity to bring the public along with what officials have been privately discussing for years. Better to lay an informed case now, rather than abruptly announce basing options at AUSMIN later this year or when the 2015 Defence White Paper is released.

* Disclosure: Lockheed Martin is a corporate member of the Lowy Institute.

Image courtesy of @TonyAbbottMHR.