UK, Japanese, Italian partners agree on next steps for fighter jet

I can see they sacrificed top speed for range. Looks like a Mach 1.6 range jet similar to the F-35 and the J-35.

This is a dangerous choice as JASDF would be lacking a Mach 2 class jet able to counter the J-20 and the KF-21 Block 3 Mach 2 class jets by 2040s.

The GCAP fighter is designed to be supported by unmanned wingman combat drones. The combat drones will be designed as part of the GCAP program, so it is a wider program than just one fighter design. The GCAP fighter is designed to replace UK and Italy's Eurofighters, and Japan's Mitsubishi's F2s.

The UK is running both FCAS (future combat air system) and GCAP fighter programs at the same time. The FCAS fighter program and GCAP program have some similarities, however, the FCAS fighter is being solely designed by the UK and is unsupported by combat drones. By running the FCAS and GCAP programs together, the UK gets advantages from both going it alone, and joining Italy and Japan.

The UK is running both FCAS (future combat air system) and GCAP fighter programs at the same time. 

No. FCAS is a joint French, German, Spanish cooperative development program. The British have no involvement in that program.

Btw, FCAS is the program publicly aiming to develop manned and unmanned aircraft and team them. GCAP has not explicitly stated it is going that route.

I can see they sacrificed top speed for range. Looks like a Mach 1.6 range jet similar to the F-35 and the J-35.

Laughable. How can you possibly know the top speed of an aircraft that is yet to be prototyped? You, like me, have no access to their modeling or to their Key Performance Parameters.

No. FCAS is a joint French, German, Spanish cooperative development program. The British have no involvement in that program.

You're correct. However, confusingly, there are two FCAS programs. One run solely by the UK, which is the one I was referring to, and the other one that you correctly stated is run by France, Germany, and Spain.

https://en.wikipedia.org/wiki/Future_Combat_AirSystem(UK)

Why worry so much about details. It will never be build except for maybe 2 or 3 prototypes. The delays will make it obsolete long before it goes into production.

Aside from China's J-20, South Korea's 4.5-generation KF-21 fighter jet, which is only in the development stage, cannot serve as a benchmark.

This is because this joint development will be a sixth-generation fighter, with the main focus being to develop a fighter similar to or better than the F-22. Koreans can be praised for their rich delusions.