Video footage captured the moment a domestically built hypersonic boost-glide vehicle, developed and tested by South Korea, struck the water at the conclusion of its flight. Weapons testing at South Korea's Agency for Defense Development covered the missile in question.

The system would extend Seoul's capacity to place targets across the border within striking range, analysts note, at a time when both sides of the peninsula continue building up their respective arsenals. The Hyunmoo-5, equipped with a large unitary warhead designed to reach fortified underground installations, preceded this system, and both weapons align with the Korea Massive Punishment and Retaliation doctrine that guides the country's deterrence posture.

Heading into the terminal phase, where velocities climb to their peak, boost-glide weapons can carry enough kinetic force to penetrate hardened underground structures. Alongside a hypersonic cruise missile powered by air-breathing propulsion, the country's defence programme encompasses new ballistic missiles intended for launch from both naval vessels and submarine platforms. No timeline has been set for when a deployable version will enter active use.

Seoul's security calculations have expanded to place both China and Russia alongside North Korea as sources of ongoing concern.

Defined by speeds exceeding Mach 5 — roughly 6,100 kilometres per hour — these weapons divide into two broad classes. Rocket propulsion carries glide vehicles to altitude, after which a portion of them follow erratic flight paths on the way to their intended destination, according to their design specifications. Scramjet propulsion and similar engine technologies allow cruise missiles to maintain hypersonic velocities throughout sustained atmospheric flight.

Whereas ballistic missiles trace paths that analysts can calculate in advance, these two weapon types are reported to retain the ability to adjust their trajectories during flight and to operate at altitudes low enough to stay beneath radar detection range.

Tracking data gathered during Operation Sindoor illustrated that even a supersonic projectile places a considerable burden on air-defence systems. Travelling at close to three times the speed of sound and hugging the terrain, such a projectile would enter ground-based radar range at roughly 15 kilometres out, leaving defenders approximately 15 seconds before it reached its target. Travelling at Mach 5, a projectile can cross that same stretch of ground in fewer than nine seconds — a velocity that places it beyond the interception range of the majority of surface-to-air missile systems, which are reported to operate below that threshold.

Constructing vehicles capable of operating at hypersonic velocities poses well-documented engineering obstacles — thermal loads at those speeds demand sophisticated heat-management solutions, sustaining combustion inside a scramjet engine remains an unresolved technical challenge, and the ionised gas layer that forms around the airframe tends to interfere with both navigation signals and communication links. Three engineering realities slow progress on low-altitude high-speed flight: structural components must tolerate intense mechanical strain, propulsion systems draw considerably more energy at low altitude, and the infrastructure needed for testing remains both rare and expensive to operate.

Among the weapons under development are a testbed vehicle — the Hypersonic Technology Demonstrator — recorded at Mach 6, a successor cruise missile designated BrahMos-II targeting speeds near Mach 7, a glide platform known as the Dhvani, a naval strike weapon called the Long Range Anti-Ship Missile built to engage surface vessels up to and including aircraft carriers, and a further cruise system catalogued under the designation ET-LDHCM, or Extended Trajectory-Long Duration Hypersonic Cruise Missile.

Three weapons programmes form the backbone of the United States effort: the air-launched AGM-183, a scramjet-driven system known as the Hypersonic Air-breathing Weapon Concept (HAWC), and the Navy's Conventional Prompt Strike missile. Deployed aboard ballistic platforms, the DF-17 carries the DF-ZF glide vehicle — a manoeuvring warhead rated between Mach 5 and Mach 10 — while a separate orbital-delivery system underwent flight evaluation in 2021.

Deployed in active conflict in Ukraine, the Kinzhal missile reaches speeds around Mach 10, while the Tsirkon — a vessel-launched variant — operates at roughly Mach 8. Three hypersonic and precision-strike programmes are advancing on separate national tracks — the V-MaX in France, the Southern Cross experiment through an Australian-American partnership, and a glide projectile tailored to Japan's island-defence requirements — with all three scheduled to reach deployment readiness by 2030.