Two theories came about. 1st was that it was the Argentine sub that was missing....but that was quickly put aside. The second was from a "insider" saying that is was rouge elements in China that did not like the leader's friendliness and working with Trump that undercut him by supposedly launching the missile from one of their rouge subs and it was with the China's leaders permission the sub and missile were taken out.
No proof, just internet rumors.
Intercept anecdotes were all around the morning it happened, and deep state, China variant, knew a hit on Hawaii would WWIII us.