For many years, while the Japan Air Self-Defense Force (JASDF) has boasted advanced equipment, it has consistently lacked reliable offensive weaponry. Even though domestically developed air-launched missiles were introduced, the actual number deployed has been minimal. This situation is now changing—recently, the United States announced its approval of a new batch of extended-range Joint Air-to-Surface Standoff Missiles (JASSM-ER) for Japan. These long-range stealth cruise missiles will be mounted on Japan’s F-15J, F-35A, and F-35B fighter jets. Analysts suggest that these air-launched stealth cruise missiles will significantly enhance Japan’s preemptive strike capabilities, posing a greater threat to neighboring regions than the previously acquired Tomahawk cruise missiles.
According to Japan’s latest announcement, the U.S. State Department approved the arms sale agreement, which includes 16 JASSM-ER missiles, along with training ammunition, anti-jamming GPS receivers, support equipment, and software. The total value of the deal is approximately $39 million, with Lockheed Martin as the primary contractor. Previously, the U.S. had approved the sale of 50 such missiles to Japan, forming a key part of the JASDF’s initiative to upgrade its existing F-15J fighters.
For Chinese observers, the JASSM series air-launched cruise missile is a familiar weapon—the U.S. military has long regarded this stealth cruise missile as a core asset to counter the People’s Liberation Army (PLA). It has even been depicted in U.S. think tank war games as a pivotal tool in “shifting the balance in a Taiwan Strait conflict.” For Japan, however, which has historically lacked long-range strike weapons, this is a rare acquisition. On January 18, 2024, Japan formally signed a contract with the U.S. to procure 400 Tomahawk cruise missiles, all to be installed on Japan’s Aegis destroyers—a deal widely celebrated in Japanese media. However, from a technical perspective, the Tomahawk cruise missile, whose design dates back to the 1970s and 1980s, has notable limitations despite numerous upgrades. Its slow flight speed, relatively fixed flight path, and lack of stealth make it vulnerable, with limited penetration capabilities.
In contrast, the JASSM-ER missile poses a far greater threat. As a stealth, subsonic, long-range air-launched land-attack cruise missile, its U.S. Air Force designation is AGM-158B, with a range of nearly 1,000 kilometers. It is specifically designed for precision strikes against high-value targets. The missile utilizes a combination of GPS and inertial navigation systems for mid-course guidance, while its terminal phase employs a passive infrared imaging seeker, making it resistant to conventional jamming techniques. Another major advantage is its integration of artificial intelligence technology, enabling it to intelligently plan attack routes, autonomously identify and lock onto targets, and even retarget mid-flight. Its accuracy is claimed to be “within meters.”
The U.S. Defense Security Cooperation Agency (DSCA) stated that this sale will “enhance the operational capabilities of Japan’s Self-Defense Force fighter jets (including but not limited to the F-15J and F-35A/B) by providing advanced long-range strike systems, thereby strengthening Japan’s ability to address current and future threats.”
According to the UK-based FlightGlobal website, another potential platform for the JASSM-ER missiles is Japan’s domestically developed F-2 fighter jet, which is essentially an enlarged version of the American F-16. The report also mentioned that Japan had previously experimented with using the domestically produced C-2 tactical transport aircraft to air-drop JASSM-ER missiles mounted on “Rapid Dragon” ammunition pallets, effectively converting the transport aircraft into a makeshift bomber.
In addition, the JASSM-ER has another derivative model—the LRASM (Long Range Anti-Ship Missile, AGM-158C)—which has also garnered significant interest from Japan’s Self-Defense Forces, with dedicated funding allocated for live testing.
Although the JASSM-ER missile has a shorter range compared to the Tomahawk cruise missile (1,600 km), its deployment on agile fighter jets provides a much greater operational strike radius than the Tomahawk. Combined with its stealth and intelligent targeting capabilities, the acquisition of JASSM-ER missiles significantly increases the threat Japan poses to surrounding regions. Japan claims that these advanced land-attack missiles “can preemptively intercept and neutralize invasions of Japan at long range and in early stages.”
From this perspective, Japan’s deployment of JASSM-ER stealth cruise missiles on advanced fighter jets represents a considerable threat. However, on the other hand, it remains uncertain whether the U.S. can supply Japan with sufficient quantities of these precision-guided weapons. According to previous U.S. think tank war games, in the event of a large-scale conflict between China and the U.S., the U.S. military’s stockpile of precision-guided munitions, including JASSM-series missiles, would be depleted within a week of the conflict’s outbreak.
The Asia Times in Hong Kong also highlighted concerns about the aging of U.S. infrastructure, the lack of skilled workers with professional expertise, and instability in supply chains, all of which limit America’s ability to ramp up weapon production. Observers are worried whether the U.S. can meet its own Pentagon demands for equipment, let alone provide sufficient support to allies like Japan.
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