China's experimental stealth corvette, first spotted at the Liaonan Shipyard in 2023, has undergone a notable modification: the missile launcher previously fitted on its deck has been replaced with an unidentified boxy system. Defense Blog reported the change this month, and naval open-source analysts are split on what the hardware is—some suggest a shipborne sonic weapon designed to disorient enemy crews, while others point to a high-power microwave (HPM) system intended to neutralize incoming drone swarms.
Directed energy: the new frontier in naval warfare
The sonic theory draws on China's documented use of acoustic devices for non-lethal maritime harassment and riot control. The HPM theory, however, is bolstered by the system's placement and boxy profile, which resemble recent Chinese land-based directed-energy weapons built to fry the electronics of small unmanned aerial vehicles from beyond three kilometers. Naval warfare researchers note that adapting directed-energy technology onto stealth warships offers a practical countermeasure against cheap, massed drone attacks that can exhaust standard missile defenses.
While no official confirmation exists regarding the module's exact purpose, the modification underscores the test ship's primary mission as a flexible trials platform for evaluating emerging weapons, sensors, and low-signature naval technologies at sea. The War Zone (TWZ) noted in August 2024 that the vessel features smooth, planar, and faceted low-observable surfaces to minimize radar signature. It also includes a main gun concealed within a stealth cupola, lid hinges suggesting a potential vertical launch system (VLS), and a modified mount resembling an HQ-10 missile launcher, though with a single aperture likely for electro-optics, laser testing, or mockup evaluation. Its streamlined mast and potential hybrid all-electric propulsion point to concepts aimed at advancing future littoral combatants.
Gray-zone coercion and sonic weapons
China has already employed non-kinetic weapons and directed-energy systems in its gray-zone operations in the South China Sea, where hostilities are kept below the threshold of armed conflict through ambiguity and deniability. In January 2025, the China Coast Guard (CCG) reportedly used a long-range acoustic device (LRAD) to harass the Philippine Coast Guard (PCG) ship BRP Cabra. In late 2023, China may have deployed the same weapon against ships operated by the Philippine Bureau of Fisheries and Aquatic Resources (BFAR), following a previous incident early that year in which it used a military laser against the PCG ship BRP Malapascua, temporarily blinding the crew.
Unlike traditional loudspeakers that project sound in a spreading cone, an LRAD projects powerful sound in a focused beam, similar to a flashlight. While intended for ship-to-ship hailing and crowd control, the weapon can cause serious injuries. Yue Li and other writers note in an April 2025 article in the peer-reviewed Chinese Journal of Traumatology that intense sound inflicts acoustic trauma, eardrum rupture, ossicle fractures, and hearing loss. Depending on frequency, infrasound can induce organ resonance, dizziness, and organ damage, while ultrasound generates thermal energy, causing tissue burns, visual blurring, internal pain, and bone fractures.
High-power microwaves: a plausible answer
China has been at the forefront of developing HPM weapons, making it plausible that the mystery device on its stealth test corvette is one such system. Microwave weapons have also figured in speculation surrounding the unexplained medical symptoms known as “Havana Syndrome,” despite disputed foreign attribution—highlighting how an invisible and difficult-to-attribute means of attack could theoretically lend itself to gray-zone coercion. A Chinese HPM attack against a law enforcement vessel from a rival claimant state could temporarily incapacitate the crew, destroy the target's on-board electronics, and force a mission abort, while maintaining plausible deniability and avoiding high-profile media exposure.
For ship defense purposes, HPMs are designed to defeat drone swarms over a wide area by delivering electromagnetic pulses, which cause voltage spikes, overheating, and arcing, destroying sensitive electronic components. Stealth warships may be particularly vulnerable to drone swarms, as heterogeneous drones carrying optical, radar, infrared, magnetic, and acoustic sensors could detect targets across multiple signatures. Large numbers of strike drones and unmanned boats could bypass a warship's layered defenses. While shipboard defenses might defeat most attackers, those that slip through could cause major damage.
Defeating a drone swarm may require prodigious amounts of ammunition and expend limited interceptor stocks. A June 2026 South Korean military exercise showed that even eight 20-millimeter Vulcan guns firing simultaneously at 1,000–3,000 rounds per minute at close range struggled against a 50-drone quadcopter swarm flying slowly in formation: successive bursts destroyed 44 drones, while infantry using shotguns and hand lasers eliminated the remainder. In a real drone attack, the swarm would not fly in a slow, coordinated fashion; it would attack from multiple directions and possibly combine with anti-ship missiles and unmanned surface vehicles (USVs) to maximize the chances of a hit.
Underscoring the threat USVs pose to large surface warships, private US drone firm Seasats released footage in July 2026 of its US$240,000 Lightfish USV closing in on a Chinese Type 052D destroyer in the South China Sea. The incident highlights how inexpensive unmanned systems can challenge even the most advanced fleets, a dynamic that is reshaping naval planning across the Indo-Pacific. As China continues to test directed-energy systems on its stealth corvette, the race to field effective countermeasures against drone swarms and gray-zone tactics is accelerating, with implications for regional security from the South China Sea to the Taiwan Strait.
