Kurt Rinehart, Cadet, US Air Force Academy
Dr. Kalyn Howard, Major, US Air Force Academy
Background
The evolving threat landscape in the Indo-Pacific region underscores the critical importance of air base defense for protecting US interests. With the People’s Republic of China (PRC) developing sophisticated low-level cruise missile technologies, existing defense postures are insufficient, especially on the US westernmost territory of Guam. The plan to defend Guam, however, needs improvement. The Department of Defense must face the harsh realization that it is too late to develop, approve, and implement brand new defense technologies for their strategic position in the Indo-Pacific region. Rather, we must shift focus toward utilizing existing technologies in innovative ways to defend our bases in this region. The benefits of this shift to current technology include that it can be rapidly fielded, the capabilities are well known, and the deployment costs are certain.
This article presents a cost analysis of radar defense solutions for the island of Guam in the event of an attack from a low-level cruise missile threat. We analyzed four distinct postures, including novel applications of existing technologies. By assessing coverage, cost, and operational effectiveness, this study aims to inform strategic investments in air base defense to mitigate vulnerabilities in the Pacific region.
Threat Environment
The PRC’s advancements in low-level cruise missiles pose significant challenges to air base defense. These weapons could theoretically travel at altitudes as low as 250 feet and speeds of 500 mph. The United States’ current horizon-limited radars only provide an estimated 4-minute response time from first detection of a low-level cruise missile to impact on target. Extending the detection range will provide additional response time and space for movement and maneuver.
Research Method and Specifications
This study evaluates the cost and effectiveness of four radar defense postures over a 10-year period to provide a first look cost estimate for enhancing Guam’s air base defense, utilizing existing technologies in non-traditional ways, namely, through integration with maritime assets. All cost analysis was done looking at a single azimuth, rather than aiming to determine how many of each of these defense systems would be required to defend the entire island. The systems analyzed include the Ground-Based Sentinel A-4, Ground-Based Tethered Aerostat Radar System (TARS), Sea-Based Sentinel A-4, and Sea-Based TARS.
Low-level cruise missiles exploit the line of sight of traditional radar systems which cannot see beyond the horizon, significantly limiting the effective range compared to when traditional systems are tracking a higher altitude threat. Placing traditional radar systems on sea vessels can extend the detection range of low-level cruise missiles simply by allowing these radar systems to be deployed further away from the point of defense. This results in increased warning time for incoming threats. However, this approach introduces challenges, including the need for specialized maritime expertise, increased operational costs, and coordination with naval assets.
Our cost analysis below of each system includes procurement, maintenance, operational training, and personnel expenses over a decade. Key performance metrics include effective range, warning time, and coverage capabilities. The Lockheed Martin Sentinel A-4 radar system used in two of the defense postures analyzed in this study has an effective range of 70 miles, limited by the horizon requires two personnel to operate, and costs approximately $7.5 million per unit. Given that the capabilities of the Sentinel A-4 are not public, these figures are rough estimates and do not reflect the true capabilities of the system. The TARS used for this cost analysis has an effective range of 200 miles (affected by the horizon, depending on deployment altitude), requires five personnel for the launch and recovery of this airborne system, and costs $11.25 million per unit. A downside of the TARS system is that it must be replaced every five years.
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The sea-vessel used for the two sea-based postures discussed previously is the Swiftships 36-Meter Missile Retriever. This vessel was chosen due to the unique position it holds of being the only sea vessel already in service with the US Air Force, as these are currently used in the Gulf of America to retrieve drones after they are shot down in exercises over the Eglin Range. Purchasing new ships, built utilizing the existing industrial capacity, would take 1-3 years at a total cost of approximately $23 million per unit. These vessels can be expected to have a longer service life and improved supportability over other vessels due to the existing supply chain infrastructure. Alternately, repurposing some of the existing fleet could enable more rapid fielding in Guam.
Results
Table 1 compares the four options. These options consist of two radar defense systems (the Sentinel A-4 and the TARS), in either ground- or sea-based deployment. Each system’s cost, coverage, and warning time are evaluated to determine their suitability for enhancing Guam’s air base defenses against emerging threats. Taking this information, as well as other costs for associated expenses such as manning requirements, maintenance, fuel, and many other factors, these are the results for each of the analyzed defense systems. All warning times are measured from first detection of a threat to time of anticipated impact. All costs are adjusted for inflation at an average of 2.65% per year.
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Notably, the Ground-Based Sentinel A-4, which is most comparable to the current Guam defense posture, is outperformed by all other COAs in the “effectiveness” metrics of coverage and warning time. A cost-benefit analysis of the options is depicted in Table 2. This table demonstrates the effective coverage benefits of the TARS system and the substantial cost differential between sea- and ground-based systems.
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Analysis and Discussion
Based on these results, the Ground-Based Sentinel A-4 is the lowest cost solution but also the least effective, as indicated by the low coverage and warning time. The Ground-Based TARS presents a balanced solution with improved range and warning capabilities at moderate cost. Sea-based options, while offering operational agility, mobility and extended warning times, also incur significantly higher expenses, which must be balanced for widespread implementation.
Given the financial and operational constraints, Ground-Based TARS emerges as the most practical solution for initial deployment on Guam. Its extended range and 15-minute warning time provide a substantial improvement over current estimated capabilities (with a Ground Based Sentinel A-4), addressing the immediate threat from PRC low-level cruise missiles. For wartime scenarios which demand agility and responsiveness, Sea-Based TARS could serve as a supplementary system in high-risk areas, or areas that require radar coverage in many different places in a short amount of time. Leveraging joint partnerships could improve the feasibility and lower the cost of these sea-based options substantially. Additionally, this study only used Guam as a baseline for the cost analysis. Given the re-introduction of numerous WWII era airfields in the Pacific, sea-based radar platforms could be advantageous because they have increased survivability as mobile targets. With proper placement, the sea-based radar options could also provide coverage in strategic locations between key defense points.
Both ground-based and sea-based systems demand specialized training. Incorporating a mix of uniformed personnel and civilian contractors can optimize costs and operational efficiency. However, reliance on contractors increases long-term expenditures anywhere from one to three times what it would cost active duty members to perform the same job, so it may be more advantageous to train airmen to operate these systems. This would advance the case for using land-based radar defense methods, rather than having to train personnel, or hire contractors, to operate sea vessels. Under a PRC-conflict scenario, reliance on contractors for a wartime mission set introduces a slew of considerations for the DoD, including operational agility, contractor safety, and the status of contractors under international law. These are some of the factors that must be considered when choosing between uniformed service members or contractors when implementing a defense strategy of this nature.
Conclusion
Enhancing air base defense on Guam is imperative for maintaining US strategic deterrence in the Indo-Pacific. This study identifies Ground-Based TARS as the most cost-effective initial solution, offering a significant improvement in coverage and warning time without incurring prohibitive costs. While Sea-Based TARS provides superior capabilities, its high cost may limit its viability for widespread use. Joint partnerships could improve the feasibility and cost-effectiveness of sea-based options. DoD senior leaders will need to decide whether the operational agility is worth the higher price tag and advocate accordingly. By adopting a unique toolbox, the United States can effectively bolster its defensive posture against emerging threats from near-peer adversaries.
Cadet Kurt Rinehart is a Management major, US Air Force Academy, CO, who will be graduating in Spring 2025 and commissioning as a pilot.
Major Kalyn Howard, PhD, is a Logistics Readiness Officer and Assistant Professor of Management, US Air Force Academy, CO.
The views expressed in this article, book, or presentation are those of the authors and do not necessarily reflect the official policy or position of the United States Air Force Academy, the Air Force, the Department of Defense, or the U.S. Government.