China builds an electromagnetic kill zone in the South China Sea

With a surge of hidden electronic warfare upgrades, China is reshaping the South China Sea into an electronic battlespace tilted decisively in its favor.

This month, the Asia Maritime Transparency Initiative (AMTI) reported that China has quietly expanded its electronic warfare and surveillance infrastructure across its artificial island bases in the disputed Spratly Islands. The upgrades, implemented between 2023 and 2025, bolster China’s ability to monitor and contest activity in the South China Sea, a strategic waterway claimed by multiple nations.

Satellite imagery shows new antenna arrays and mobile electronic warfare vehicles deployed on Fiery Cross, Mischief and Subi reefs. At least six paved sites with monopole antennas were installed, each oriented toward the sea. The facilities appear linked to vehicle-mounted jamming systems designed to target specific electromagnetic bands. At Subi Reef, a roofed shelter was built in 2025 to house the units, while Mischief Reef hosts five vehicles connected to fixed arrays.

Additional upgrades include a circular concrete platform at Mischief Reef, for rapid antenna deployment, and two new radomes at Subi Reef, mirroring earlier installations on Fiery Cross and Mischief. These radomes provide overlapping intelligence, surveillance, and reconnaissance (ISR) coverage. China also constructed fortified coastal emplacements at Mischief Reef, capable of hosting artillery or mobile weapons.

Outlining the threat that China’s electronic warfare capabilities pose to the US and its allies in the South China Sea and in the Taiwan Strait, a November 2025 report by the US-China Economic and Security Review Commission (USCC) states that these capabilities target the networks that are the nervous system of US military operations.

The report notes that the People’s Liberation Army (PLA) has improved its ability to disrupt, degrade or paralyze US reconnaissance, communications and targeting systems, undermining the connectivity and situational awareness that modern US forces depend on.

It states that China’s electronic warfare assets could impair US access to satellites and networked sensors in both peacetime and conflict, adding that these advances form a core element of China’s counter-intervention strategy aimed at limiting US military effectiveness in the Indo-Pacific.

Focusing on the immediate tactical usage of these systems, J. Michael Dahm mentions in an August 2020 Johns Hopkins Applied Physics Laboratory (JHAPL) report that China could use its South China Sea outposts as powerful electronic warfare and intelligence hubs, allowing the People’s Liberation Army (PLA) to jam communications, disrupt radar and geolocate foreign forces across the region.

Dahm mentions that China’s mobile jammers, high-frequency direction-finding arrays, satellite communications (SATCOM) interception sites, and paired electronic intelligence (ELINT) on Fiery Cross, Mischief and Subi reefs can triangulate targets and overwhelm adversary sensors. He notes that, together, these systems give China the ability to control the electromagnetic spectrum, track ships and aircraft and interfere with foreign militaries operating in contested waters.

Illustrating how China could use these electronic warfare capabilities against the US, the South China Morning Post (SCMP) reported in December 2024 that China’s electronic warfare blueprint for a South China Sea conflict centers on crippling the US Navy’s carrier strike groups by targeting its most critical sensors and data-sharing systems.

According to the report, priority targets include the AN/SPY-1 phased-array radar on Aegis ships, vulnerable to jamming, drone-generated false returns and noise saturation. It also says China aims to disrupt the E-2C Hawkeye’s fleetwide coordination role and exploit US signal transponders to infiltrate or overload the Cooperative Engagement Capability (CEC) network. It notes that by severing wireless links and degrading shared targeting data, China seeks to blind the carrier group and undermine its integrated air-defense architecture.

In addition, SCMP reported in July 2024 that China used electronic warfare in the South China Sea by deploying AI-enabled, networked radars and shipborne sensors that neutralized the jamming tactics of the US Navy’s EA-18G Growler.

The report states that Chinese warships, including the Type 055 cruiser Nanchang, fused data from multiple radars and maintained high-speed fleetwide communications to resist Growler-generated noise, false targets and electromagnetic attacks. It adds that by linking ships into an integrated “kill web,” the PLA countered US jamming, preserved radar lock on key US assets, and even advanced aggressively to block a carrier group. It also adds that Chinese commanders reported that Nanchang’s radar functioned normally despite US jamming attempts, forcing US aircraft and ships to pull back.

China’s electronic warfare capabilities may already have downed US aircraft in the South China Sea. For instance, Paul Crespo mentions in an October 2025 Real Clear Defense article that the loss of a US Navy MH-60R Sea Hawk helicopter and an F/A-18 Super Hornet fighter, which crashed within 30 minutes while operating from the USS Nimitz in the South China Sea that month, may have been caused by China using electronic warfare to confuse aircraft systems.

Crespo notes that China’s electronic warfare assets are capable of disrupting GPS, communications, and avionics, potentially rendering aircraft uncontrollable. He adds that by targeting electromagnetic bands used by US forces, China could have interfered with critical avionics, contributing to the reported downing of US aircraft in the contested region.

However, no official investigation has publicly confirmed electronic warfare as the cause, and evidence about the incidents, while consistent with electronic warfare interference, remains circumstantial.

At the strategic level, China’s electronic warfare capabilities on its occupied features in the South China Sea contribute to securing its sea-based nuclear arsenal. Chi Guocang mentions in a September 2020 China Maritime Studies Institute (CMSI) report that China’s push for a submarine bastion in the South China Sea hinges on creating a dense reconnaissance and defensive network that shields its nuclear ballistic missile submarines (SSBNs) from detection.

Chi notes that the completion of large Spratly outposts allows China to build a “relatively complete reconnaissance and defense system” to support hidden SSBN operations in the region’s complex waters. He notes that such a system – implying integrated sensors, surveillance, and electronic protection – would help Chinese submarines maneuver, evade foreign tracking and maintain continuous nuclear deterrence patrols while minimizing exposure to US and allied monitoring forces.

In contrast to China’s advances in electronic warfare, Lieutenant General John Caine, in response to policy questions the US Senate Armed Forces Committee posed in April 2025, has stated that US joint forces are inadequately protected against adversary electronic warfare attacks. He notes that the US has “lost some muscle memory” after decades of operating in a permissive spectrum and that near-peer adversaries such as China have rapidly advanced their electronic warfare capabilities.

Caine also emphasizes that US electronic warfare training ranges and simulation capabilities are inadequate, lacking the fidelity and complexity needed to prepare for modern threats. He argues that these gaps present a significant risk to readiness, making improved training, investment, and spectrum access essential for maintaining electronic warfare superiority.