And it has happened to others that almost certainly weren't trying to kill each other: In 2009, a French and a UK ballistic missile sub collided https://en.wik

And it has happened to others that almost certainly weren't trying to kill each other: In 2009, a French and a UK ballistic missile sub collided https://en.wikipedia.org/wiki/HMS_Vanguard_and_Le_Triomphant_submarine_collision https://en.wikipedia.org/wiki/HMS_Vanguard_and_Le_Triomphant... not to mention quite a few more incidents of subs ramming surface vessels, which should be even easier to avoid.