“I will accept nothing less for our nation than the most effective, cutting-edge missile defence systems,” President Trump said at the Pentagon last week. He was there to launch the Missile Defense Review (MDR), the final major national security review of his first term. “We have the best anywhere in the world. It’s not even close,” he surmised.

The MDR is a comprehensive review of US capability to defend itself against missiles of all types: ballistic missiles, cruise missiles and new hypersonic weapons being developed by China and Russia. But for US allies like Australia, the MDR could have significant implications and foreshadows some tough debates that may be ahead for the alliance.

The review follows the release of the National Security Strategy in 2017 and the National Defense Strategy and Nuclear Posture Review, both released last year. The MDR, rumoured to have been completed for more than a year, was delayed due to ongoing negotiations with North Korea. The administration was fearful that releasing a policy which promised to invest significant money in new technologies and strategies with the aim of countering Pyongyang’s ballistic missile capability would derail any talks taking place.

This appears to have been overly cautious. Negotiations with North Korea are still ongoing, and in the end the MDR is for the most part a status-quo document. It follows many of the prescriptions of the Obama administration’s Ballistic Missile Defense Review released in 2010, but has expanded to cover all varieties of missiles and the protection of military forces overseas, as well as the American homeland.

The most worrisome idea that the Trump administration was toying with was not fully embraced by the MDR: investing in space-based missile interceptors.

The most worrisome idea that the Trump administration was toying with was not fully embraced by the MDR: investing in space-based missile interceptors. Essentially a resurrection of the Strategic Defense Initiative – or as Senator Ted Kennedy labelled the Reagan administration’s missile defence plans, ‘Star Wars’ – the MDR calls for a six-month review into the feasibility of space-based interceptors; kicking the can down the road. While it’s unclear whether the technology is available or if the costs are even acceptable, placing missile defences in space would be extremely destabilising, encouraging arms racing and potentially even the eventual placement of missiles or weapons in space as other countries sought ways to overcome them. Even then, there’s no guarantee the idea would work.

While the MDR doesn’t go as far as placing interceptors in space, it does call for a new network of missile-detecting sensors to be installed in orbit. The main reason for this is that the technological landscape is shifting rapidly when it comes to missiles, with advances in new capabilities, like hypersonic vehicles, outpacing efforts to defend against them.

Hypersonics, using either 'scramjet' or 'boost-glide' technologies, are highly manoeuvrable and can travel between 5,000 and 25,000 kilometres per hour, faster than many current missiles. If they are successfully deployed, modern defences that work by shooting down enemy missiles in the three phases of their flight path – ‘boost’, ‘mid-course’ or ‘terminal’ – will not be able to stop them. China has conducted several successful tests of hypersonic vehicles and is reportedly “concentrating” significant resources in their research and development. The Trump administration’s response to this problem is to build a network of space-based sensors that will allow rapid, early detection of missiles “almost anywhere on the globe”.

Rplacing missile defences in space would be extremely destabilising, encouraging arms racing and potentially even the eventual placement of missiles or weapons in space as other countries sought ways to overcome them. Even then, there’s no guarantee the idea would work.

The implication is that once these missiles are detected while still on the ground, the best defence may be a good offence. The MDR talks about developing a strategy of “active missile defense” where US combatant commanders will be asked to develop “complementary attack operations” that will supplement traditional missile defence capabilities. Allies, it says, will be needed to integrate their capabilities for “active missile defense” and “as appropriate, attack operations capable of striking the entire range of infrastructure supporting adversary offensive missile operations”.

This new strategy of ‘active missile defence’ could have significant implications for US allies like Australia. For one, Indo-Pacific Command will likely seek to more fully integrate Australia and the ADF into its regional military plans, using Australian military forces to help locate and potentially destroy adversary missile launchers and infrastructure, including those still based within their territory. This could be highly risky – adversaries may misperceive an allied strike on its territory as threatening its nuclear arsenal or regime survival, leading to a spiral of uncontrolled escalation that may not be in Australia’s interests.

The other implication is an Australian role in facilitating access to a new space-based sensor network. Research by the late Des Ball – recently popularised in ABC’s televised drama Pine Gap – reveals that the joint-facility near Alice Springs is heavily involved in the relay, processing and analysis of data from American intelligence satellites, and already plays a critical role in detecting missile launches like those from North Korea. Any new, advanced, space-based sensors will require terrestrial relay and processing centres like that at Pine Gap, making facilities in Australia a critical node in any next-generation ‘active’ US missile defence system. This may open-up such facilities as critical targets for adversaries in the region looking to disable or prevent any regional US missile defence strategy.