When Radio Silence is Not Enough: Signature Suppression & the Fight for Surprise

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‘The next fight will be a battle of signatures. Assume everything we do can and will be observed. We are going to have to fight to get to the fight’[1]

Digitalisation is both a blessing and a curse. A blessing in that complete force connectivity is expected to seize the initiative by realising rapid decision-cycles and response agility during the controlled chaos of combat. However, it is apparent there is also an increasing price to be paid for digital capability advantages being progressed by the Australian Defence Force (ADF). The ‘price’ is primarily in relation to detectable signatures of radio frequency wavelengths in the electromagnetic spectrum. Digitalisation of military systems harnesses this invisible electromagnetic energy in increasingly sophisticated ways to enable joint operations. So a growing reliance on electromagnetic physics means military force elements may be at greater risk of being seen, identified and targeted by adversaries. To date the ADF has enjoyed relatively unimpeded use of electromagnetic energy, but this may be set to change.

Therefore, winning the signature battle in future conflicts may mean the difference between joint warfighting mission success and a national tragedy.

This strategic hazard is especially pertinent to an Army developing amphibious expeditionary capability. Army is reliant on Royal Australian Navy (RAN) strategic lift assets surviving transit in the maritime domain. Thus in context of emerging anti-ship ballistic and hypersonic scramjet missiles, including naval assault drones, enterprise risk is rising for the RAN and embarked land forces enroute to future high-intensity war zones. So whilst digitalisation is a key component of force modernisation and should continue to be advanced with vigour, it is vital the ADF makes a herculean effort to harness low-signature technologies.[2] Joint signature coordination and joint deception doctrine will also be essential to prevail in future spectrum warfare.

‘The notion of fighting to get to the fight and accepting it as inevitable your force will always be located by adversary intelligence, surveillance and reconnaissance (ISR) assets well in advance, is not a mindset that ADF planners should subscribe to.’

Noting the growing risk from modern anti-ship technologies, detection avoidance planning should be a high priority as the land force mission may depend on it. In context of an Amphibious Task Group (ATG) sailing to a future Indo-Pacific area of operations, observing disciplined radio silence procedures is a useful start, but it will not be enough to evade detection. Instead a multi-faceted stealth approach using clever deception measures[3] and low-signature or signature masking technologies may enable avoidance of a risky maritime fight on the way to the joint land battle.[4] ATG fleet assets could also ‘outsource ISR’ to maintain a blackout of active radar, active sonar, data and voice transmissions for the entire journey to avert location compromise.  Passive radar[5] and sonar to see without being seen should also be the rule and not the exception.[6] Moreover, messages between vessels during a voyage may have to resurrect old techniques, such as Morse-code via signal lamps.[7]  Alternatively, innovative technologies could be explored, such as secure, high data rate laser communications that transmit via photons[8] in lieu of radio frequencies that might be detected from strategic distances.[9] Long-range surveillance could also be provided by imagery and signals intelligence from tactically launched small satellites.[10][11] High-altitude strategic stealth drones could compliment the common-operating picture provided by space-based assets, so surface fleet assets do not risk exposing their position with active transmissions.[12] Thus a combination of drones and small satellites may provide further risk reduction, due to system redundancy and layered ISR effects during electromagnetic emissions lock-down.[13]

The key point to note is the land force is at its most vulnerable when embarked at sea during high intensity conflict. So a healthy conversation is necessary with our friends in the RAN to ensure escalating strategic risks are fully understood and mitigated.[14]

But while this strategic vulnerability is not new, the hazards are elevated due to evolving naval weapon systems and lower detection thresholds. An adversary could therefore go to great lengths to interdict the land force while they are still at sea in an easily identifiable Landing Helicopter Dock.[15]  So should the ATG be recognized early, continuously tracked and repeatedly targeted during a future war, the huge investment of national resources in raising, training and sustaining a potent land force could actually prove futile.[16] Therefore, stimulating enthusiastic Defence enterprise and industry effort to produce comprehensive signature management technologies and joint deception measures is recommended for strategic risk mitigation. Ultimately, the idea that fighting to get to the fight will be inevitable is not a course of action the ADF with finite resources should be resigned to. However, while eluding detection cannot be guaranteed, resolute attempts to suppress ATG signatures and mask approach vectors may manifest in survivability dividends, as fighting for surprise endures as a winning Principle of War.

About the author

Lieutenant Colonel Greg Rowlands is an infantry officer with 27 years of Army service. He is a graduate of Australian Command & Staff College and the Capability & Technology Management College. Greg has also completed an undergraduate degree and three master’s degrees from the University of New England, University of Canberra and University of New South Wales.

[1]37thCommandant to the US Marine Corps General Robert B. Nellor Message to the Force 2018 ‘Execute’.
[2]This includes development of acoustic minimisation or masking technology, radar absorbent materials, infra-red retarding paint/materials, thermal management and stealth technologies.
[3]Deception measures could include taxonomies of dummy networks, naval and air drone manoeuvres, offensive cyber operations and ‘fake news’ to direct attention away from where the ATG is actually tracking.  Cyber deception measures were discussed in my previous Land Power Forum post at the hyperlink.
[4]This includes stealth technologies in the design of future RAN ships, such as hybrid electric drives to reduce acoustic and thermal signatures, angular flat surface construction for smaller radar cross-sections, hull water sleeting to minimise sonar signature and cool air induction in the mack to limit infra-red signature.
[5]Observe without being observed technologies are being developed by startups like Silentium Defence.
[6]Passive systems use ambient features of the environment and the target to detect them, while not revealing the sensors location. Risk will need to be managed with subsurface threats and restricting active sonar.  Underwater autonomous drone screens providing an ATG outer security perimeter may be a potential solution.
[7]Quad-copter drones could also be used to carry messages between ships, but this would need to be balanced with the risk probability of radio frequency emissions from drone control links being detected.
[8]Lasers can transmit data in the visible light and infra-red range of the electromagnetic spectrum. Therefore, laser communication photons may possibly be seen by direct-line of sight quantum detectors scanning the correct area at time of transmission.  But lasers might not be so noticeable at strategic distances like radio frequencies can be.
[9]Laser communication is a highly secure, instantaneous means of communication that features gigabit data transfer rates that are difficult to detect or disrupt.
[10]Any identification of threats to the ATG would need to be communicated via a rapid data burst packet transmission to reduce the likelihood of detection and interception by an adversary. Secure laser communications might also be employed.
[11]Small satellites could also facilitate strategic communications via SATCOM downlinks.  ATG force elements could receive messages but refrain from transmitting responses. This space support concept is discussed in my space capability posts on the Land Power Forum at the hyperlink.
[12]These drones would need to be controlled from another location well away from the ATG to avoid detection of radio frequency drone command links in the ATG, hence the ‘outsourcing’ of ISR missions to other ADF force elements.  Drone command stations could be based in Australia or other deployed locations at sea or on land. Careful drone flight path planning/deception would be necessary to avoid revealing the ATGs likely position.
[13]Electromagnetic emissions restrictions may be lifted if the ATG was attacked.  However, the threat situation would dictate RAN procedures for various states of battle-readiness and active systems employment in transit.
[14]This includes the Royal Australian Air Force, our allies, industry and the intelligence community to compliment the wider threat picture analysis and capability options available.
[15]Targeting Australian troop ships and hospital ships have occurred in previous conflicts, such as the SS Ceramic and AHS Centaur that were torpedoed and sunk in WWII.
[16]If the ATG were tracked too early in transit to its destination, it would provide greater time and flexibility for an adversary to conduct maritime strike planning – the strategic initiative and element of surprise would be lost. This includes vectoring missiles, submarines, surface vessels or long-range bomber forces to intercept the ATG.