1. The Japanese outrage has a lot more to do with trying to get US forces out of Okinawa than it does with the sailors who were killed.
2. The fishing trawler actually hit the submarine from behind, although the sudden surfacing of the submarine gave it no chance to avoid impact. The sub did not ram the trawler as the Japanese endlessly repeat.
3. The accident happened in an area of the sea marked as a place where submarines practice such maneuvers. Admittedly, it is unclear what the trawler could have done differently except not fish there.
4. There has been almost no mention of a very similar incident a few months earlier in which a Japanese submarine sank a Japanese fishing boat near Japan.
5. There is no money in the budget for an aircraft to fly above the submarine and ensure that no stray vessels are near the projected maneuver.
6. While the submarine had previously heard the trawler, it could not hear it before the ascent as it was below the temperature boundary, and once it was on the way up there was no time to track surface vessels.--Stephen V Cole
There are a few points not widely known about the unfortunate incident in which a US submarine collided with and sank a Japanese trawler near Hawaii.