Cruise Missile Variant Of Navy’s JSOW Glide Bomb Is On The Chopping Block

The powered JSOW variant had been intended, in part, as a long-range stand-off weapon that the Navy’s F-35Cs could still carry internally.

byJoseph Trevithick|
AGM-154 Joint Stand-Off Weapon (JSOW) photo


The U.S. Navy has reversed its plans to field a stealthy cruise missile derived from the AGM-154 Joint Stand-Off Weapon glide weapon, or JSOW. In lieu of these previous plans to acquire the AGM-154E Joint Stand-Off Weapon-Extended Range, or JSOW-ER, the service is now looking to buy another type of stealthy cruise missile, a design related to the AGM-158B Joint Air-to-Surface Standoff Missile-Extend Range, or JASSM-ER. The expectation had been that the Navy's F-35C Joint Strike Fighters would be able to carry JSOW-ERs internally, allowing them to employ the weapons while flying in their stealthiest configuration, something they will not be able to do with the JASSM-ER.

The Navy's latest budget request for the 2022 Fiscal Year, which it released on May 28, 2021, as part of the larger U.S. military-wide budget proposal, makes clear that it has abandoned the JSOW-ER effort. The service has asked for no funding for JSOW research and development in the coming fiscal cycle because of that decision and the completion of work on cryptographic upgrades for the datalinks on the AGM-154C-1 JSOW variant. Separately, the service confirmed to Aviation Week that it had decided to purchase what it described as JASSM-ERs.

An unpowered AGM-154 Joint Stand-Off Weapon (JSOW) glide bomb., MKFI via Wikimedia

"JSOW Extend Range development has been removed from the program roadmap," the budget documents state bluntly. "The Navy has decided not to pursue JSOW ER capability."

The section of the US Navy's Fiscal Year 2022 budget request dealing with JSOW-related research and development., USN

The budget documents do not provide any additional information as to the reasons why the Navy made this decision.

In 2019, the Navy had announced plans to issue a sole-source contract to Raytheon, the current manufacturer of the JSOW, for the development of the JSOW-ER derivative. At that time, it expected to begin fielding these weapons, integrated onto its F-35Cs, as well as F/A-18E/F Super Hornets, no later than 2023.

What the Navy's exact requirements for the JSOW-ER were are unclear, but Raytheon had previously pitched two different powered JSOW derivatives, both of which had the same general form factor as the original unpowered glide bomb. The company had flight-tested the second design, which had a Hamilton Sundstrand TJ-50 turbojet installed in the tail, in 2009, reportedly demonstrating its ability to hit targets out to a distance of nearly 265 miles.

The tail end of a JSOW-ER prototype showing its turbojet engine., Raytheon

Those earlier powered JSOW designs also carried over the pop-out wings from the original glide weapon, the first examples of which began entering service in the 1990s. The original AGM-154A version carried a load of 145 BLU-97/B cluster bomblets. Depending on the release profile, AGM-154s, which have a very small radar cross-section, can glide to targets up to 70 miles away. 

The JSOW-ER would've given the weapon significant additional stand-off range, which is increasingly valuable as potential near-peer opponents, such as Russia and China, as well as smaller adversaries, continue to expand and modernize their air defense capabilities. Unpowered JSOWs already give Navy jets an important stand-off weapon for engaging enemy air defense assets. The new cruise missile would also have been able to leverage the JSOW's modular payload capability, as well as other upgrades it has received over the years, giving it added flexibility. 

The aforementioned AGM-154C-1, which carries a multi-part warhead designed to penetrate hardened targets, also has an imaging infrared seeker that gives it increased accuracy and the ability to target moving ships. That seeker is also immune to electronic warfare jamming.

The basic AGM-154C, as well as other AGM-154 variants, including the A model with its cluster munitions payload and the A-1 variant with its 1,000-pound-class high-explosive warhead, can only be used against fixed targets using their GPS-assisted inertial navigation system guidance package. All of the JSOW types that remain in U.S. military service have also been upgraded with two-way datalinks that allow them to receive new targeting information in flight, as well. You can read much more about the JSOW in detail in this past War Zone feature.

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On a number of levels, scrapping the JSOW-ER for the extended-range variant of the increasingly popular and combat-proven JASSM family makes sense. The U.S. Air Force removed its JSOWs from service in 2008, leaving the Navy as the only U.S. military service still employing those glide bombs. 

In addition, other portions of the Navy's budget proposal say that its JASSM-ER will not just be a standard AGM-158B, but will instead be a service-specific version of that weapon that also leverages components of the AGM-158C Long-Range Anti-Ship Missile (LRASM). LRASM is derived from the core JASSM design. The Navy says its JASSM-ER version will, as a result, have both anti-ship and land-attack capabilities.

Details about the Navy's JASSM-ER variant as laid out in the service's Fiscal Year 2022 budget proposal., USN

In 2018, the Navy achieved an early operational capability with LRASM on the Super Hornet. The Navy now plans to integrate LRASM onto its F-35Cs, as well as its P-8A Poseidon maritime patrol aircraft, and the Air Force has also added that weapon to the B-1B bomber's arsenal

An artist's conception of an F-35 Joint Strike Fighter carrying a pair of AGM-158C LRASMs under its wings., Lockheed Martin

It's also worth noting that Lockheed Martin, which produces the JASSM series, has integrated the AGM-158A variant onto older F/A-18 Hornet variants for both Australia and Finland. All of this could help simplify the process of adding the JASSM-ER to the available arsenals for the F/A-18E/F and F-35C, as well as ease logistics and sustainment burdens. With the Air Force pursuing multiple new JASSM variants right now, it could open a pathway to additional capabilities for Navy jets down the line, too.

At the same time, JASSM series missiles, to include the LRASM, are too big to be carried internally on any variant of the F-35. This had been one of the clear potential benefits of the JSOW-ER, which would give Navy F-35Cs, as well as potentially F-35As flown by the Air Force or foreign allies and partners, extra stand-off capability while operating in their most stealthy configuration. Carrying JASSMs or LRASMs externally on pylons under the wings can only impact those jets' stealthy characteristics, though it still offers them a valuable stand-off capability. The JASSM-ER's range is at least 575 miles, significantly greater than the demonstrated range of the TJ-50 turbojet-powered JSOW, according to publicly available information. Under contract from the Air Force, Lockheed Martin is now working on a JASSM-XR variant that could have a range of more than 1,000 miles, while still retaining the same form factor as the AGM-158B. 

It is also important to note that the Navy will continue to field unpowered JSOW variants, which can be carried internally on the F-35C.

An F-35C with its internal weapons bays open showing it carrying a pair of AGM-154 JSOWs, as well as two AIM-120 Advanced Medium-Range Air-to-Air Missiles (AMRAAM), during a test., Lockheed Martin

The JSOW-ER isn't the only new stand-off weapon in development that the Navy's F-35Cs could carry internally, as well. Just this year, the Norwegian Defense Materiel Agency, or Forsvarsmateriell (FMA), in cooperation with the U.S. Air Force, conducted the first test launch of a Joint Strike Missile (JSM) cruise missile from an internal weapons bay on an F-35A. 

The JSM, which Norwegian defense contractor Kongsberg is developing together with Raytheon in the United States, and that a number of international F-35A operators are already looking to acquire, is an air-launched derivative of Kongsberg's surface-launched Naval Strike Missile (NSM). The NSM, a weapon the Navy and the Marine Corps are acquiring for ship and ground-launched use, respectively, is primarily an anti-ship weapon, but has a secondary land-attack capability.

A US Air Force F-35A Joint Strike Fighter prepared to launch a Joint Strike Missile during a test in February 2021., FMA

In addition, it's not clear if the Navy's decision to drop out of the JSOW-ER program spells the end of that project completely. In November 2020, the U.S. government approved a potential sale of various aircraft munitions to the United Arab Emirates. That package included 50 AGM-154Es, among other things. Raytheon could certainly seek to finish work on this weapon as a private venture and offer it for export. A dozen countries, including the United States, have unpowered JSOWs in service and could be interested in the cruise missile derivative. That would also give the Navy an easy way to circle back to the JSOW-ER in the future, should it decide to do so.

For now, at least, the Navy has made clear that it no longer has any intention of buying cruise missiles based on the JSOW glide bomb design.

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