Duty to Assist getting medical records

I got a Navy Veteran that was station in Okinawa Japan  and was hospitalized for throat cancer. he has medical records there…>   he got out of the Navy in 2018… he was transferred to San Diego calif   Navel Base  had some more operations on his throat…so he has medical records at both these places.

I understand our medical records stay at the place we had medical work done  for 7 years before they go to the NRPS in St Louis….ok I told him to contact these bases where he had this medical work done  and request all his Medical records at both places   San Diego and Okinawa Japan Navel hospital …he needs to sigh the FOIA and send it to both these places requesting his Medical records.  with his return address.

OK he has filed a claim for this   he has a hole in the top of his mouth  and  the VA messed up on the surgery  but he has since got that surgery he needed….

Question? Is it the VA responsibility or the Duty to Assist Him in getting these Medical Records?? Can he request the VA to get these Medical Records for him or for the VA to look at these records that would help substantiate his Claim?

I know the Navy and Marines  &.US Coast Guard  get their Medical Records at different places   where as to the US Army and Air force is at different places.