The lead for this radar case came from Jan Aldrich in the form of a Project Record Card. While searching the BB site for other documents regarding the 24 June radar incident, described in the PRC shown below, the sightings listing and 28 scope photos showed up.
The case was already listed, and listed as unknown with the proper ID number, on the 1953 UFO Chronology as:
June 24, 1953; Iwo Jima, Bonin Islands (BBU 2605)
11:30 p.m. Crew of USAF KB-29 aerial tanker plane. Radar tracked an unidentified target that twice approached to within 0.5 mile of KB-29, and once to within 6 miles. (Berliner).
There's a June 18th entry on the BB sightings listing which referred to a file 2612 and mentions scope photos, but file 2605 (seen clearly on the folder prior to the photos) says it's June 18th. Either the date is wrong or BB number is wrong. Brad Sparks lists the June 24 incident with the BB Unknown number of 2605.
Both Iwo Jima entries are listed as explained in the unclassified listings, but the secret list down below says the June 24 incident was unsolved.