| Dates | 18–24 November 1964, with the main incidents on 19 and 24 November |
| Location | Atlantic Fleet Weapons Range, vicinity of Puerto Rico |
| Naval unit | USS Gyatt, a guided-missile destroyer with, per the file, the latest and most accurate radar |
| Aircraft | US Navy F-8 Crusader fighters |
| Object | Delta-shaped, about the size of a jet fighter, estimated speed in excess of Mach 3 |
| Radar | Held for 21 minutes on 19 November; recorded on motion picture film of the radar scope |
| Total plots | At least six high-altitude, high-speed plots across the period |
| Initial explanation | The commanding officer at Ramey AFB identified the object as a YF-12A |
| CIA finding | Not a YF-12A or similar Lockheed aircraft; probably a delta-wing type with significantly higher performance than the F-8 |
| Classification | Top Secret, handled via BYEMAN controls, OXCART project access only |
| Documents | CIA-UAP-D022 and CIA-UAP-D023, released 7 August 2026 |
The Puerto Rico 1964 encounters are a series of unidentified radar and visual contacts over the Atlantic Fleet Weapons Range between 18 and 24 November 1964. A Navy destroyer tracked an object for 21 minutes and filmed its radar scope; an F-8 Crusader pilot watched a delta-shaped object pull away from him at an estimated Mach 3 in full moonlight. The CIA's own OXCART office ruled out America's secret Mach 3 aircraft as the explanation. The files were declassified on 7 August 2026.
This case has had almost no press attention since the release, which is strange, because of everything in the fifth batch it has the cleanest evidential shape: instrument data, a trained observer, an obvious mundane explanation, and the one organisation on Earth qualified to test that explanation writing down that it does not hold.
What Happened on 19 November 1964
The Atlantic Fleet Weapons Range off Puerto Rico was, and is, a live test area. In November 1964 missile firings were scheduled there, which matters later.
On the night of 19 November, the USS Gyatt picked up a high-speed, high-altitude target on radar. The contact stayed on the ship's scope for twenty-one minutes. During that time it closed on a Navy fighter from astern, coming in to within four miles.
The Crusader pilot got a look at it. Conditions were as good as they get at night: full moonlight, good weather, good visibility. He described a delta-shaped object roughly the size of a jet fighter, flying with what the briefing notes call very high performance, and he estimated its speed in excess of Mach 3.
"The Crusader pilot on the night of the 19th observed the UFO in full moonlight, weather was good, visibility was good. UFO was identified as a Delta shaped object about the size of a jet fighter."— CIA-UAP-D023, Briefing Notes, November 1964
Five days later, on 24 November, the weapons range again held a high-speed, high-altitude target. This one pulled away rapidly from a second Crusader that was at the time flying at Mach 0.99 and 45,000 feet. That is an F-8 at the top of its performance, being left behind.
The Radar Evidence
What lifts this case above a pilot's word is that the Navy filmed its radar scope, and the CIA then had the film analysed.
One honest caveat belongs here. Radar of this era produced anomalies — weather returns, propagation effects, interference — and a filmed scope is only as good as the set that produced it. The CIA analysts were aware of this and asked their own scientific intelligence office to look for anything further the photography could yield. What they were left with was a consistent, long, fast track that matched what the pilot had described seeing.
The Obvious Answer: America's Own Secret Aircraft
In November 1964 there was one straightforward explanation for a delta-shaped object doing Mach 3 over the Caribbean, and it was American.
Lockheed's A-12, built for the CIA under the codename OXCART, was flying in secret from Groom Lake. Its Air Force sibling, the YF-12A, had been publicly acknowledged earlier that year. Both were delta-planform aircraft capable of sustained flight above Mach 3 at extreme altitude — the only things in the world that could do it. Anyone told about a Mach 3 delta over the Atlantic would reach for that answer first.
The commanding officer at Ramey Air Force Base did exactly that. According to a cable from the Commander, Caribbean Sea Frontier, Atlantic Fleet command was informed that the UFO had been identified as a YF-12A. Case closed, apparently.
Except the CIA did not let it close. A memorandum dated 1 February 1965, from the Assistant Director for Special Activities — the directorate that ran OXCART — to the Assistant Director for Scientific Intelligence, records the opposite conclusion.
"CINCLANTFLT was informed that UFO identified by CO Ramey as being YF-12A. We think ONI finally convinced, through our efforts, that UFO in fact not YF-12A or similar category Lockheed Aircraft."— CIA memorandum, 1 February 1965, BYE 2081-65
Read that again with the security markings in mind. This memo sits inside the BYEMAN control system, restricted to people cleared for OXCART. It is not a public statement, or a press line, or a denial issued to a newspaper. It is the programme office telling its own scientific intelligence colleagues, in the most restricted channel available to them, that the aircraft was not one of theirs — and going to the trouble of persuading Naval Intelligence of the same thing.
That is the most valuable sentence in the file. Almost every Cold War UFO case carries an unfalsifiable objection: it was probably a secret American programme, and the people who know cannot say. Here, the people who knew did say.
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What the CIA Concluded
Ten days later, on 11 February 1965, the Assistant Director for Scientific Intelligence delivered his assessment. It confirms the scale of the episode: not one contact but at least six high-altitude, high-speed plots off Puerto Rico across the 18 to 24 November period, with apparently valid radar contacts and observations of unidentified aircraft near the weapons range on multiple dates.
On the object itself, the finding is measured and precise. Taking the radar photography and the pilot's observations together, the assessment concluded the object was probably a delta-wing vehicle of a type with significantly higher performance than the F-8 that chased it — and, from the associated correspondence, that the objects reported during the period remained unidentified.
The assessment also worked the alternatives properly, which is worth crediting.
RULED OUT
The YF-12A / A-12Ruled out in writing by the office that ran the programme, which then persuaded the Office of Naval Intelligence of the same. This removes the only American aircraft capable of the observed performance.
CONSIDERED
A Soviet MiG-21 from CubaThe Gyatt was about 21 nautical miles from the eastern tip of Cuba and within MiG-21 range, and the USSR had a reconnaissance MiG-21 fitted with an AFA-39 camera and possibly side-looking radar. The file states there was no evidence of any such flights from Cuba by Soviet or Cuban pilots — and a MiG-21 cannot approach Mach 3.
CONTEXT
A reconnaissance target of opportunityMissile test firings were scheduled at the weapons range during the period. The assessment notes it is conceivable the tests would have been an attractive target for reconnaissance — a motive for someone to be there, but not an identification of who.
OPEN
What it actually wasThe assessment settles on a delta-wing vehicle outperforming the F-8, without being able to say whose. The Office of Naval Intelligence had no further information and was asked to report similar incidents in future.
"We think ONI finally convinced, through our efforts, that UFO in fact not YF-12A or similar category Lockheed Aircraft."
— CIA, Assistant Director for Special Activities, 1 February 1965Who Was Briefed
The second document, CIA-UAP-D023, is a short set of briefing notes headed for a Mr Walter Elder, summarising the incidents of 16, 19, 21 and 24 November. Elder was a senior figure in the Director of Central Intelligence's own office, which tells you how far up this went.
The notes are two pages, written in the compressed style of something meant to be read standing up: the Gyatt's radar track, the Crusader pilot's observation, the Mach 3 estimate, the 24 November repeat, and a closing line recording that the Office of Naval Intelligence had nothing further and had been asked to flag similar incidents in future. There is no speculation in them at all.
Timeline
16–24 November — the encounters
At least six high-altitude, high-speed unidentified plots are logged near the Atlantic Fleet Weapons Range off Puerto Rico, with the main events on 19 and 24 November.
19 November — the Gyatt track
The USS Gyatt holds an object on radar for 21 minutes and films its scope. An F-8 Crusader pilot sees a delta-shaped object in full moonlight and estimates its speed above Mach 3.
24 November — the second incident
A high-speed target pulls away from a Crusader flying at Mach 0.99 and 45,000 feet.
1 December — the wrong answer
A cable records that Atlantic Fleet command has been told the object was identified by the commanding officer at Ramey Air Force Base as a YF-12A.
1 February — the CIA disagrees
The Assistant Director for Special Activities writes that the object was not a YF-12A or similar Lockheed aircraft, and requests scientific analysis of the Navy's radar film.
11 February — the assessment
The Office of Scientific Intelligence concludes there were at least six plots, and that the object was probably a delta-wing type with significantly higher performance than the F-8.
7 August — declassified
Both files are published at war.gov/ufo in the fifth PURSUE release, sixty-one years after the analysis was written.
Why This Case Deserves More Attention
Cold War UFO cases usually die on the same objection. Whatever was seen, it was probably an American black programme, and the people in a position to confirm or deny were not going to do either. It is a reasonable objection and it has quietly closed hundreds of files.
Puerto Rico 1964 is the rare case where that objection was tested at source. The only aircraft in the world capable of the observed performance belonged to the CIA and the Air Force. The CIA office responsible for it examined the case, concluded the object was not theirs, and took the trouble to convince Naval Intelligence too — inside a channel where there was no audience to perform for and no reason to say anything but what they believed.
What was over the weapons range that week is still unknown. The file's own answer is a delta-wing vehicle outperforming a front-line Navy fighter, of unidentified origin, seen at least six times in a week over a live missile test range. Sixty-one years later that is where it remains.
The same 2026 release contained the Cold War telegram traffic and the early Air Force files we cover in the Project SIGN file and the Navy's film analysis. For an earlier CIA case from the same era, see our post on the declassified CIA report on a green object over a Soviet missile range.
Read the Files Yourself
Both documents are public domain and free to download from war.gov/ufo, catalogued as CIA-UAP-D022 (six pages, Top Secret / BYEMAN / OXCART) and CIA-UAP-D023 (two pages of briefing notes) in Release 05. Note that the release filename dates D022 to 1965, which is when the CIA processed it — the encounters themselves took place in November 1964. Our index of the primary sources is in the UAP document archive.