Joint Strike Missile

The Joint Strike Missile is an air-launched cruise missile built by Kongsberg Defence & Aerospace and designed from the start to fit inside the F-35A’s internal weapons bay. It is a sibling of the ship-launched Naval Strike Missile, sharing the same low-radar-cross-section airframe shaping and seeker family, but with revised geometry, fuel volume, and software for an air-launched profile. Norway, the launch customer, declared an initial JSM capability on its F-35A fleet in 2023, ending a long integration programme that began in the late 2000s and ran through a series of test drops over the Utah Test and Training Range.

Range is the headline number. Kongsberg quotes a reach of around 500 kilometres on a high-low profile, which puts a launching F-35A well outside most modern integrated air-defence engagement zones. The missile cruises subsonically and sea-skims through the terminal phase, with terrain-following over land. Guidance is layered: GPS-aided inertial navigation for the cruise, a passive imaging infrared seeker for the terminal phase, and an automatic target recognition library that lets the missile pick a specific ship class out of a cluttered scene without an active emission that could give the launcher away. A two-way datalink allows in-flight retasking and post-launch updates from the carrier aircraft or another node. The 120-kilogramme warhead is modest by anti-ship standards, but the system trades raw warhead mass for the ability to be carried internally by a stealthy fighter.

Beyond Norway, Japan has been the most consequential customer. Tokyo signed a foreign military sale through the United States in 2019 to integrate JSM on its F-35As as part of its long-range strike build-up, and has continued to expand the order. Australia announced a JSM acquisition in 2023 to arm Royal Australian Air Force F-35As, framing it as a stand-off maritime strike capability for the western Pacific. The United States Air Force and Navy have funded JSM integration work on the F-35 as part of the joint programme office’s weapons roadmap, although operational fielding on US aircraft has lagged the European and Asian customers.

Development is still moving. Kongsberg and RTX agreed in 2023 to co-produce JSM components in the United States, and an extended-range variant has been discussed in Norwegian budget documents. The missile’s natural competitor in the F-35 internal-bay anti-ship role is the air-launched LRASM , which is larger, carries a heavier warhead, and is currently external-carry only on the F-35 — a contrast that has shaped how each customer parcels the two weapons across its fleet.