As hard as it may be to believe, in his later years Kurosawa simply could not get the funding he needed to keep working (at the level he demanded of himself) from within Japan or the Japanese studio system.
It took deals with investors and companies in Europe and the US plus a lot of support from folks like those mentioned above, in order for him to get those last few films made.
One of my favorite things is to spot a Kurosawa reference or inspiration in somebody else's work. Which is why the absence of the no-brainer in "1941" annoyed me, because I was just
waiting for it. There's a scene where the German officer aboard the Japanese sub pulls a gun on Mifune's character (who is commanding the sub) and I thought, oh, Mifune's gonna take out a knife or something and throw it into the German's gun hand. BUT NO.
It would have made sitting through that thing almost worthwhile.