Japan has doubts about the pace of GCAP. Faced with feared delays, Tokyo is considering more F-35s to hold out until 2035 without compromising on codes and AI.
Summary
The GCAP is Japan’s major aviation venture with the United Kingdom and Italy: to bring into service around 2035 a new-generation fighter jet intended to replace the Mitsubishi F-2 on the Japanese side. On paper, the program offers Tokyo something that purchasing an American aircraft does not fully guarantee: real leeway in terms of software sovereignty, freedom to modify, updates, and, in the future, control of functions related to onboard AI. But the timeline is cause for concern. Sources cited by Reuters in May 2025 indicated that Tokyo already feared a delay beyond 2035, or even towards 2040 if the European pace does not accelerate. In this context, the idea of purchasing additional F-35s or extending the F-2 becomes a credible transition scenario. The issue is simple: Japan wants a sovereign aircraft, but it cannot afford to wait too long in an environment where China, Russia, and North Korea are increasing pressure.
The GCAP is as much a sovereignty program as it is a combat program
The Global Combat Air Program was announced in December 2022 by Japan, the United Kingdom, and Italy. Its official objective is clear: to develop a new-generation combat aircraft by 2035. In December 2023, the three countries signed the treaty creating the program’s intergovernmental organization, the GIGO, with headquarters in the United Kingdom. The program is therefore no longer a vague political agreement. It has a formalized institutional and industrial framework.
For Tokyo, the stakes go far beyond simply acquiring a more modern aircraft. The Japanese Ministry of Defense explains in black and white that air superiority is a prerequisite for the country’s defense, and that complete dependence on a foreign partner would cause Tokyo to lose its operational initiative. This is why Japan insists on a “Japan-led” development of the future fighter, with a domestic industrial base, national maintenance, and the ability to make rapid changes.
This logic is central. Japan did not join the GCAP to buy a European aircraft. It joined to co-own part of the technological power over a future combat system. This is a major difference from an “off-the-shelf” purchase, even at a very high level.
The GCAP is not like the FCAS, even though both programs are targeting the same generation
A clear distinction must be made between GCAP and FCAS/SCAF. Both are aimed at a new-generation air combat system. Both are based on a “system of systems” approach, with a piloted fighter, drones or remote effectors, advanced sensors, and a networked combat architecture. But their political and industrial structures differ significantly.
The FCAS, led by France, Germany, and Spain, is built around a New Generation Fighter, remote carriers, and a combat cloud. On paper, it is a very ambitious package. In practice, the program is being slowed down by deep disagreements over governance, intellectual property, operational requirements, and industrial sharing. The differences between Dassault and Airbus are no longer simply industrial friction. They go to the heart of the program. France wants compatibility with its nuclear and naval aviation needs, which is not a priority for Germany.
The GCAP, on the other hand, has so far demonstrated tighter governance. The United Kingdom, Italy, and Japan have made faster progress on the legal framework and management structure. This does not mean that everything is going well. It means that, so far, the program has been less bogged down by obstacles than its European rival. This is one of the arguments put forward by those who see the GCAP as a more fluid program than the FCAS.
The most important difference, from the Japanese point of view, lies elsewhere: the GCAP was designed from the outset to meet the need to replace the F-2 around 2035, with a Japanese emphasis on freedom of modification and the ability to rapidly upgrade the aircraft. This point is much more explicit in Japanese doctrine than in FCAS communications.
Japan is growing impatient because the schedule is threatening to slip where it cannot afford to do so
The heart of the problem is the schedule. Reuters reported in May 2025 that Japanese officials were concerned that the GCAP would not meet its 2035 target. According to these sources, a lack of urgency on the European side could push deployment beyond 2040. For Tokyo, this is not simply an administrative delay. It is a direct capability risk.
The Japanese Ministry of Defense points out that the F-2 is due to begin leaving service around 2035. If the GCAP does not arrive on time, Japan will find itself facing a very real vacuum: its current aircraft are aging, even as the regional environment becomes more hostile. The ministry’s official website explicitly cites the rise of Chinese fighters, including the J-20, as well as Russian activity around the Su-57 and the heavy Okhotnik drone. Japan is therefore not thinking in terms of laboratory research. It is thinking under geographical pressure.
Japan’s impatience is also due to a strategic gap. The United Kingdom and Italy are pursuing the GCAP with a view to industrial power, exports, and longer-term renewal. For Japan, the program is primarily a response to a direct operational need in relation to China. The level of urgency is not experienced in the same way. This is often where multinational cooperation begins to become strained: everyone signs the same sheet, but not for the same reasons.
The buzz surrounding the American F-47 has heightened this pressure. Even though the specifications and final schedule remain largely classified, the fact that Washington relaunched its NGAD fighter in March 2025 has brought the question of timing back to the center of the debate. In Tokyo, this reinforces the idea that the transition window must be secured, rather than endured.
Sovereignty over source codes and embedded AI is the crux of the matter
The most strategic issue for Tokyo is not just the airframe or the engine. It is the software. The Japanese Ministry of Defense insists on “freedom of modification” in order to allow for “timely and appropriate” upgrades in the future. This wording should be taken seriously. It means that Japan wants to retain control over software changes, the integration of new sensors, the evolution of mission functions and, more broadly, how the aircraft can be adapted to rapidly changing threats.
In a new-generation fighter, this issue is decisive. Aircraft are increasingly becoming flying computer systems. Performance depends on data fusion, onboard processing, secure communications, electronic warfare, sensor management and, in the future, AI components designed to assist the pilot, prioritize information or coordinate remote sensors and effectors. If a country does not have control over these software layers, it owns the aircraft without really owning its evolutionary trajectory.
In 2025, the British Parliament emphasized that, in the GCAP, data is at the heart of the system and that artificial intelligence is destined to play a role in its assimilation and analysis. This does not mean an autonomous “warrior autopilot” in the simplistic sense of the term. It means that AI becomes a capability multiplier in combat management, threat prioritization, sensor exploitation, and decision-making acceleration. For Japan, losing control of these building blocks would be tantamount to buying a future aircraft already partially locked in by others.
This is precisely why Tokyo preferred the GCAP to a purely American solution. Reuters summed up the Japanese calculation well: joining the GCAP allows Japan to co-own the embedded technology, which would be much more difficult to obtain with an equivalent American aircraft. This is the real political leverage of the program.
GCAP technologies aim for a global leap forward, not just a successor to the F-2
The GCAP is not designed to be an “improved F-2.” The stated ambition is to create a new-generation aircraft with stealth capabilities, advanced sensors, enhanced connectivity, networked weapons, and the ability to cooperate with unmanned platforms. Manufacturers talk about digital engineering, new development methods, and an architecture designed for faster evolution than previous programs.
One of the technological pillars identified for 2025 is the ISANKE & ICS architecture — Integrated Sensing and Non-Kinetic Effects & Integrated Communications Systems — supported by a consortium including Leonardo UK, ELT Group, and Mitsubishi Electric. Behind this acronym lies a system that combines sensors, communications, electronic warfare, and non-kinetic effects. This is exactly the type of architecture that will make the difference in modern air combat: detecting earlier, understanding faster, jamming, degrading, and transmitting better than the adversary.
Japan is also working in parallel on collaborative unmanned systems. Its ministry has already indicated that the development of the future fighter will be accompanied by work on systems including unmanned aerial vehicles. This brings the GCAP closer to the latest Western architectures: a centrally piloted, but not isolated, aircraft.
This sophistication justifies the schedule, but it also explains why Tokyo is concerned. The more the program piles on software bricks, sensors, data fusion layers, and human-machine cooperation ambitions, the more difficult it becomes to keep the 2035 promise without very strict industrial discipline.
Using more F-35s would be a useful bridge, but not a real strategic answer
Faced with the risk of delay, Reuters reported that Tokyo was considering two transition options: purchasing additional F-35s or extending and modernizing some of the F-2s. The F-35 option is the most obvious. Japan has already ordered a total of 147 F-35s, making it the program’s largest foreign customer, with 105 F-35As and 42 F-35Bs. Expanding this fleet would fill part of the capability gap faster than domestic development.
The F-35 has a simple advantage: it exists, it is in production, it is interoperable with the United States, and it allows Japan to quickly strengthen its fleet, including its maritime posture with the F-35B carried on Izumo and Kaga class ships. In the short term, this is the most realistic option.
But it is not the real long-term solution. An additional purchase of F-35s reduces the immediate risk, not the structural dependence. With the F-35, Japan does not obtain the same degree of control over software architecture, major upgrades, or certain operational limitations that it is seeking with the GCAP. In short, more F-35s can buy time. They do not buy the technological decision-making sovereignty that Tokyo wants to secure for the post-2035 period.
There is also a political and budgetary constraint. Reuters reported that, on the Japanese side, some elected officials were hesitant to place new orders when not all of the aircraft already ordered had been delivered, especially the F-35B version. The bridge therefore exists, but it comes at a real financial and political cost.
The decisions that Tokyo must make are as much about governance as they are about the budget
If Japan wants to remain credible on the GCAP, it must first tighten up the governance of the schedule. The issue is not to leave the program at the first sign of delay. That would be counterproductive. The issue is to force tighter control over technical milestones, industrial responsibilities, and international contracting. In 2025, program officials were still indicating that they were aiming to conclude the first major international contract. As long as these structural milestones do not progress at the expected pace, Japanese concerns will remain rational.
Tokyo must then lock down, in black and white, what matters most to it: access, modification, updates, and sovereignty of use over critical software layers.
The precedent of internal tensions within the program—including Italian criticism of British technology sharing in 2025—shows that political confidence is not enough. In a program of this nature, anything that is not legally secure often ends up becoming a point of industrial friction.
Finally, Japan must prepare its transition plan without ambiguity. This means quickly arbitrating between three levers: an additional F-35, a targeted extension of the F-2, and an acceleration of certain national building blocks useful to the GCAP, particularly in software, sensors, and unmanned systems. Waiting for the delay to be officially acknowledged would be a classic mistake: in combat aviation, you can never make up for a capability gap at the last minute.
Japan’s choice will determine whether the GCAP is a true power program or just another compromise
Japan is now faced with a very clear choice. If it focuses too much on transitional purchases, it will secure the short term but risks diluting the political significance of the GCAP. If it sticks to the 2035 schedule without demanding tougher guarantees, it runs the risk of a delay that its geography will not forgive.
The real challenge lies in keeping the promise of a new-generation fighter with real software mastery, without allowing immediate operational needs to become hostage to an overly slow program. This is a test for Japan, but also for the GCAP itself. If Tokyo does not get both the pace and the sovereignty it demands, then the program will lose its main justification for its most urgent partner. And without this Japanese urgency, the GCAP risks sliding from a power project to a compromise program, and thus into the realm where large aircraft arrive too late.
Sources
Reuters, May 30, 2025, Japan frets over fighter rollout target and weighs stopgap options, sources say
Reuters, February 12, 2026, Italy’s parliament approves 8.8 billion euros for GCAP jet fighter program
Reuters, April 15, 2025, Italy says Britain is not sharing technology on fighter project
Reuters, March 21, 2025, Trump awards Boeing much-needed win with fighter jet contract
Ministry of Defense of Japan, Global Combat Air Program, official page
GOV.UK, December 14, 2023, UK, Japan, and Italy sign international stealth fighter jet program treaty
GOV.UK, GCAP Trilateral Defense Ministerial Joint Statement
UK House of Commons Library, What is the Global Combat Air Program (GCAP?), November 14, 2024
UK Defense Committee, The Global Combat Air Program, January 14, 2025
Airbus, Future Combat Air System (FCAS), program page
Le Monde, February 20, 2026, Italy, the United Kingdom, and Japan hope to bring Germany on board their next-generation fighter jet project
Associated Press, December 14, 2023, Japan, UK, and Italy formally establish a joint body to develop a new advanced fighter jet
Live a unique fighter jet experience