China cracks a code on invisible battlefield surveillance

This month, the South China Morning Post (SCMP) reported that Chinese radar scientists have demonstrated a breakthrough system enabling aircraft to detect moving ground targets with high clarity while remaining completely radio-silent.

Led by Li Zhongyu of the University of Electronic Science and Technology of China, the team used two Cessna 208 planes in formation, with one actively transmitting radar signals and the other passively receiving echoes, to test their “space-time decoupling two-channel clutter cancellation method.”

As reported in the Journal of Radars, the test tracked three vehicles across terrain previously inaccessible to traditional radar due to clutter, range migration and Doppler noise.

Through advanced motion correction, spectrum compression and a novel matrix-based clutter suppression technique, the system isolated targets with over 20 decibels more clarity than current technologies.

The passive aircraft never transmitted signals, making it nearly impossible to detect or jam, ideal for low-probability-of-intercept (LPI) missions, according to the Journal of Radars report.

Instead of relying on artificial intelligence, the method utilizes efficient mathematical models specifically designed for real-world applications. The development could allow Chinese aircraft and missiles to silently scan battlefields, oceans or skies, identifying mobile threats without alerting adversaries.

Li called the system a world first, positioning China at the cutting edge of stealth radar capabilities amid growing global electronic warfare competition.

Explaining the complementary nature of passive and active radars, Eric Hundman mentions in a March 2025 report for the China Aerospace Studies Institute (CASI) that passive radars can often detect stealth aircraft, as they’re hard for anti-radiation weapons to target because they emit no signals.

However, Hundman says the applications of passive radar remain relatively limited due to its reliance on unpredictable external signals, narrow usable frequencies and relatively unsophisticated processing algorithms.

As for active radars, Hundman says they offer high-resolution, multi-function capabilities, combining stealth detection, surveillance, tracking and fire control in increasingly mobile and networked platforms. However, he points out that since active radars emit signals, they are vulnerable to detection by passive sensors and anti-radiation missiles.

In view of each system’s limitations, Hundman states that Chinese researchers are working to complement active radars with passive systems and pursue network integration, aiming to fuse data across platforms for a more resilient and comprehensive radar network capable of withstanding electronic and kinetic threats.

Discussing the potential operational application of the technology, the US Department of Defense’s (DOD) 2024 China Military Power Report (CMPR) states that the People’s Liberation Army (PLA) continues to make progress in the development and integration of unmanned systems, including drone swarm tactics and manned-unmanned teaming (MUM-T) concepts.

According to the report, these efforts include employing drones for intelligence, surveillance and reconnaissance (ISR), as well as electronic warfare, decoys and potentially precision strike missions in coordination with stealth aircraft.

In an April 2025 report for the Center for Strategic and Budgetary Assessments (CSBA), Travis Sharp highlights the strategic pairing of manned stealth fighters and collaborative combat aircraft (CCAs), emphasizing their complementary roles in air dominance.

Sharp says CCAs, acting as loyal wingmen, would use active radar to detect and track enemy aircraft, transmitting targeting data to stealth fighters that remain electronically silent to avoid detection.

He notes that this setup enhances survivability while extending the fighter’s engagement range, allowing long-range missile strikes before the enemy is aware.

Sharp adds that CCAs can also jam enemy radars, further complicating adversary targeting efforts. He points out that such tactics are key to improving loss-exchange ratios in potential conflicts, including in the Taiwan Strait between the US and China.

The advent of China’s purportedly sixth-generation fighters adds impetus to the development of such technology. Malcolm Davis mentions in an SCMP article this month that China’s J-36, which appears to be optimized for air-to-air combat with very long-range missiles, could achieve advanced stealth and teaming with collaborative combat aircraft (CCA).

Further, Timothy Heath mentions in the same article that sixth-generation fighters are unlikely to be involved in maneuvering dogfights but instead focus on command and control, enabling unmanned aircraft to conduct strikes against air, marine and ground targets.

Ditching manned fighters altogether, the SCMP reported in May 2025 that China’s Jiu Tan drone carrier, a super-high-altitude, long-range unmanned aerial vehicle (UAV), could carry up to 100 kamikaze drones or six tons of ammunition with a maximum range of 7,000 kilometers and an altitude of 15,000 meters.

SCMP notes that, if deployed, the Jiu Tan could contribute to the PLA’s swarming capabilities, wherein large groups of drones are released to overwhelm an adversary’s defenses.

Stacie Pettyjohn and other writers mention in a June 2024 report for the Center for a New American Security (CNAS) that China could utilize its diverse drone fleet, ranging from kamikaze to reconnaissance and loyal wingman-type systems, to saturate air defenses, rapidly close kill chains, and complicate Taiwan and US countermeasures in a conflict over the island.

Pettyjohn and others say that China holds an initial advantage due to its large, inexpensive and varied drone arsenal, which could be used to locate and strike US and Taiwanese forces with speed and scale.

They also warn that drone mass and rapid adaptation, not just innovation, is critical, citing Ukraine as a cautionary example, with China’s production capacity giving it a dangerous edge in the opening phases of a Taiwan war.

As for the US’s capability to counter drone swarms, Wilson Beaver and Ka’Von Johnson mention in a Heritage Foundation report this month that the US faces growing challenges in countering drone swarms due to fragmented capabilities, underdeveloped training and an overreliance on costly systems.

Beaver and Johnson say that while kinetic interceptors and electronic warfare tools offer layered defenses, gaps persist in small-drone detection, real-time threat identification and swarm neutralization.

They point out that directed-energy weapons, such as lasers and high-powered microwaves (HPMs), remain impractical due to issues with range, power and target discrimination.

In addition, they say most counter-drone systems are not widely fielded, few troops are trained to operate them and base commanders often lack the authority to engage drones, compounding vulnerabilities.

While the US races to patch gaps in drone defenses, China is methodically assembling a sensor-strike network designed to operate silently, resiliently and at scale.