The US Navy has unveiled plans to convert surplus oil rigs into mobile missile defense and resupply facilities, a seemingly risky and costly scheme to address rising US vulnerability to rival missile threats in the Pacific.
This month, Naval News reported that Gibbs & Cox, a Leidos company, is working to convert oil rigs into heavily armed mobile missile defense and resupply bases as part of its Mobile Defense/Depot Platform (MODEP) Concept.
The scheme, designed for oil platforms in the Western Pacific where US forces face intensifying ballistic missile threats, not least from China’s DF-26 “carrier killer” projectiles, was presented at this month’s Sea Air Space 2024 expo held in Washington DC.
MODEP is configured as a large floating island base to be deployed at an ideal distance from shore and operate independently for over 12 months. The concept seeks to help fill ballistic missile defense (BMD) capability gaps and the US Navy’s demand for an at-sea reloading solution.
BMD and depot variants can travel 5-8 knots and cover around 200 nautical miles daily. MODEP’s total endurance is expected to be 150 days with a range of 4,000 nautical miles without refueling.
The converted platform is envisioned to enhance US air defense or strike missions. With a capacity five times that of an existing Arleigh Burke-class destroyer, the MODEP could hold up to 512 vertical launch system (VLS) cells or 100 large missile launchers.
The platform could conceivably lead to a substantial reduction in risks and costs associated with land-based defense systems.
The MODEP concept also aims to support the sustainment of the US Navy’s surface combatants and nuclear submarines through an Afloat Forward Staging Base configuration. The acquisition of these surplus rigs is estimated at 10% of the cost of a BMD version.
A semi-permanent offshore military base is not a new idea. In a June 2018 Small Wars Journal article, Jose Delgado and Eviya Vitola note that, following political and security sensitivities encountered by the US in using Saudi bases for Operation Desert Shield, the US envisioned semi-permanent bases in international waters that could help reduce response time to global hotspot contingencies.
However, Delgado and Vitola point out that the idea was not feasible at the time due to its high cost, vulnerability to missile attack and ineffectiveness compared to conventional sealift capabilities.
However, expanding the idea of a semi-permanent offshore base from a staging and logistics area to encompass BMD and other mission areas may make it feasible.
Sam Tangredi discusses the concept of sea basing in an article published in the Foreign Policy Research Institute (FPRI) in October 2015. According to the writer, the idea is to use the sea similarly to land bases for various operations such as deterrence, power projection, cooperative security, alliance support and other forward operations.
Tangredi notes that sea bases can offer several benefits such as joint command, control, communications, computers, intelligence, surveillance and reconnaissance (C4ISR).
They can also provide rapid strike capabilities using stealth or non-stealth assets, help in special forces insertion, offer BMD regional airspace control, emergency medical facilities and space for joint task force command elements, and assist in positioning infantry, light armor and artillery offshore.
However, Tangredi queries if new sea-basing technologies can outpace evolving anti-access/area-denial (A2/AD) threats. He notes that while improving air and missile defenses can mitigate A2/AD threats, the problematic survivability of sea bases puts into question the practicality of investing in them.
Still, he suggests that BMD is an area where sea bases could prove useful as multiple land and sea-based sensors increase targeting accuracy.
Tangredi suggests that BMD-capable sea bases can also bridge the gap between sea and land-based BMD capabilities, noting that logistics operations that flow through sea bases can help to keep BMD-capable ships on station.
Those BMD advantages may be why Japan briefly considered a BMD-capable floating platform after canceling plans for the Aegis Ashore missile defense system in 2020.
Asahi Shimbun reported at the time that Japan considered deploying a floating offshore BMD using components from the canceled Aegis Ashore project.
However, there were doubts about the effectiveness of the offshore BMD system in providing continuous protection against North Korean ballistic missiles, which was one of the main advantages of the Aegis Ashore system.
The Asahi Shimbun report notes that keeping the system operational could be challenging due to weather conditions and maintenance issues when deployed at sea.
It also says that installing the missile defense system on a floating platform would be unprecedented and could result in significant expenses.
Considering the drawbacks of an offshore BMD platform, Japan may have settled on building massive Aegis Equipped Surface Vessels (ASEVs), especially against hypersonic threats emerging from North Korea.
Despite that, the US Sea-Based X-band Radar (SBX) may provide a concept of MODEP operations given their similar purpose as BMD platforms.
Missile Threat notes that the SBX is a high-resolution radar on a decommissioned North Sea oil rig that produces high-resolution images of incoming threat clouds, aiding BMD interceptors in deciphering between lethal objects and debris.
The Missile Threat report notes that the SBX has been used in 12 Ground-Based Midcourse Defense (GMD) system tests and has been deployed to monitor North Korea’s missile tests and US intercontinental ballistic missile (ICBM) tests.
However, the report notes that the SBX’s high resolution comes with a narrow 25-degree viewing arc, limiting its ability to track incoming missiles and leaving it dependent on other sensors for location and trajectory.
It also points out that the SBX system’s need to sail from Hawaii to the Western Pacific for optimal positioning creates a mobility drawback that requires significant notice before missile launch. At the same time, it says its deployment at sea makes it a costly and complex system.
The vulnerability of oil and gas platforms, as demonstrated in the Ukraine war, raises further questions about the military and economic sense of converting such structures into BMD-capable assets.
In a September 2023 Forbes article, David Axe recounts the Russia-Ukraine battle for the Boyko Towers in the Black Sea, noting that big, immobile oil rigs are easy targets for missiles, aircraft and drones.
Axe notes that if one of those platforms is captured by an adversary, there would be little to prevent the other side from striking back.
He also points out the difficulty of adequately resupplying such platforms under combat conditions, with personnel aboard most likely being “left out to dry” rather than adequately resupplied and defended.
Did anyone mention that such “floating” bases might easily be taken out by submarine torpedos or low-flying cruise missiles?
A mobile offshore base is a great concept. However, what is being described here is more like a forward operating base. A mobile offshore base concept is huge. It is quite capable of carrying whatever it needs to defend it self just as much as a land base does.