This has been a old live-action movie from Asia, most likely Japan. I've seen it some time in the late 80's and I think it's been black/white only.
- Earth is invaded by UFOs (small and round, like flying balls), coming from Mars.
- Japan (I think) built some kind of super spaceship, initially hidden within some secret port in some kind of island/mountain.
The spaceship looks similar to a classic battleship, but with an added drill below the front.
In the movie's finale it's revealed that this is some kind of
super weapon/bomb that has to be manually piloted by someone. When launched it starts rotating and flies (formed like a bullet but with the drill/corkscrew head).
To defend Earth, the ship is sent on a mission to Venus, where the UFOs seem to originate. I don't remember the specific reason or conclusion here.
The ship starts underwater or launches from the mountain on the island, then taking off and fighting UFOs while leaving Earth's atmosphere.