Japan and UK move towards partnership to develop combat-aircraft systems

Very recommendable! An unusual defense cooperation in the making for several years now! The fruits of Brexit! Is post WW II pacifist Japan finally becoming more proactive as China is becoming a regional hegemon?

"... On 2 February, the UK and Japanese governments made what appears to have been their first mention of an ambitious potential joint project that Tokyo had briefly discussed in Japanese text in 2018. Called ‘Jaguar’, it’s officially said to be a universal radio-frequency (RF) system. It would presumably be intended for the Japanese F-X and UK-led Tempest fighter programs. 
Separately, Japan revealed in September that it and the UK had been working together on a powerful radar technology; we can assume this would be integral to Jaguar. The UK and Japan are also cooperating on developing an advanced version of a far-flying air-to-air missile. And Rolls-Royce has proposed cooperative development of a single engine type for the F-X and Tempest programs, which are running on somewhat parallel timescales. ...
All of this wouldn’t have been imaginable only a few years ago, when Japan basically didn’t cooperate with anyone in developing defence equipment. ... The sudden partnership with Britain has become possible because in 2014 Japan began to emerge from its military-technology shell. In that year it ended a self-imposed ban on arms exports, which had largely prevented it from joining collaborative programs. ..."

Japan and UK move towards partnership to develop combat-aircraft systems | The Strategist A surprising defence-technology partnership is emerging between Japan and the UK. The cooperation is mostly preliminary but not at all basic: the two countries are working together on some of the most challenging systems used in combat aircraft. And there’s good reason to think they’ll pool resources on more such programs.