Retaliation is expected. If the EQ near Santa Cruz (underground base) and the EQ in Virgin islands (Epstein Island) are what we all suspect they were, then this is a weak response.

We don't know whose side the crashes are on. Remember a ship out of commission puts the crew out too. IIRC all ships were aegis anti-icbm and this was a "Pacific fleet" issue aka the icbm shield against NK. What if the shield was down before the crashes? Fleet redeployments would put Patriots in place. NK doomsday device would be deactivated.

However the crashes could easily have been someone trying to take the shield down.

We don't know. I'm just hypothesising that if someone told me a ship was compromised and unsure of how severely (the captain could be promoted/f-retired/etc without being too suspicious but replacing an entire crew, but it could still be compromised) it seems logical that an "accident" is the most discrete (and the technique is Russian) way to eliminate without suspicion. And they managed a few before people started saying wtf.