An article about Nazi UFOs has been published over at Big Think.

It details accounts during and after World War II about attempts by Nazi Germany to create saucer shaped flying vessels whose much greater maneuverability could have provided significant military advantage.

Joseph Epp created his first design after seeing a test flight of the Focke-Wulf Fw 61, regarded as the precursor of helicopters and he reportedly built a working vehicle witnessed in flight in Prague.

Every prototype and most of the associated documentation was destroyed to deny them to approaching Russian troops at the end of the war.

Postwar efforts in the 60s and 70s in Canada and the US had no success. 

Brinkhof concludes that reports of Nazi success with these experiments is likely false. But does so rather curiously.

There's a section titled "The truth about Nazi UFOs" and the first sentence is false according to the account he just provided.

Unlike their German counterparts, American engineers heavily documented their attempts at making a functional flying saucer.

Of the Nazi attempts in Prague he previously said:

It is unclear how much progress was actually made at the airport. When Soviet troops invaded Czechoslovakia in April 1945, the engineers were forced to destroy all the progress they had made. Every single prototype was destroyed, and only a few documents could be saved during the evacuation. These, along with testimony from the engineers involved, are the only traces that remain of this top-secret operation.

The Nazis clearly kept records. Then destroyed them (most of) only when they were about to be captured.

It necessarily undermines confidence in his conclusions.

Further, like most governments, the US has secrets. If they employed Nazi "UFO" researchers and had success with their postwar development, they might not publicize that fact for a range of reasons, eg. use of Nazi research / researchers being unpopular and wanting to keep details of technological supremacy from enemy nations like Russia.

US Government's New Stance on UFOs

Earlier this year the US government adopted a new official stance on UFOs - that being acknowledgement of Unexplained Aerial Phenomena (UAP).

The report claims that US intelligence agencies don't possess any data to indicate that UAPs are advanced technologies in operation by foreign governments or adversaries. It acknowledges the possibility that some UAPs might belong to US government or industry programs, but declined to comment apart from saying:

We were unable to confirm, however, that these systems accounted for any of the UAP reports we collected.

Inability to confirm is ambiguous language. It could mean that they failed to find any evidence that these UAPs belong to the US or it could mean that this information is classified.

Distinctly different from the unambiguous language used in relation to adversarial ownership:

We currently lack data to indicate any UAP are part of a foreign collection program or indicative of a major technological advancement by a potential adversary.

So it's possible that some of the UAPs / UFOs being witnessed today are secretly owned by the US government or corporations.

What about aliens?

The report makes no explicit reference to them but includes an "Other" category for possible explanations which could encompass them.

References

Brinkhof, Tim (October 3, 201). The strange, possibly German origin of UFOs. Big Think.

Office of the Director of National Intelligence (June 25, 2021). Preliminary Assessment: Unidentified Aerial Phenomena. United States of America.

Wikipedia. Focke-Wulf Fw 61. (viewed October 4, 2021)

Wikipedia. Nazi UFOs. (viewed October 4, 2021) [Image source]