The scientific paper "The New Science of Unidentified Aerospace-Undersea Phenomena (UAP)" (which you can read here) has many authors. The paper has this passage on page 13:
"During the last years of World War II, Allied pilots, in both the European
and Pacific theaters, began reporting unidentified aerial phenomena that in
daylight appeared to be small metallic, sometimes translucent, spheres; and
at night appeared to be spherical lights ranging from red to yellow in color
[74]. These objects, which earned the nickname 'foo fighters', would often
pace the airplanes, sometimes flying right off their wingtips. Reports were
made by pilots from the RAF, the Polish Division attached to the RAF [73],
the Royal Australian Air Force (RAAF), the South African Air Force (SAAF)
[75], and the United States Army Air Force (USAAF) [75, 73, 65, 76]."
We also have this reference on page 17:
"One of these events was witnessed by test pilot Major J. C. Wise as he prepared to perform a test of the XP-84 jet. The object was spherical in shape
and was flying against the wind at an estimated speed of at least 200 mph."
Around pages 20-21 we read of the observation by many of "green fireballs," seen in New Mexico in December 1948 and January 1949. We read this:
"Throughout December 1948 and January 1949, the number of green fireballs observed in New Mexico continued to increase and were observed by
Air Intelligence Officers at Kirtland AFB, Air Defense Command officials, a
number of distinguished scientists at Los Alamos, as well as La Paz, himself.
In addition, astronomer Clyde Tombaugh, the discoverer of Pluto (and more
than 15 asteroids), had observed a total of three green fireballs during the
wave, which he claimed 'were unusual in behavior compared to normal green
fireballs' [95]."
We are told that in February 1949 a conference was called to discuss their origin, a conference including the famous physicist Edward Teller. We read this:
"La Paz insisted that the
green fireballs could not be meteors because their trajectories were too flat,
their color too green, and that no meteoritic material had been recovered.
Teller maintained that since no sound, or sonic boom, was associated with
them, they could not be meteors but must be some kind of electro-optical
effect [65]. The conference ended with the consensus being that the green
fireballs were some kind of natural non-meteoritic phenomenon."
The paper also has this passage on page 57:
"The 'Hessdalen lights' [259] represent the prototype of anomalous light
phenomena in the atmosphere. They generally consist of multi-shaped and
multicolored balls of light, characterized by a long duration, and sometimes
by high-energy emission. The lights range in size from half a meter to 30
meters. Very short-lasting 'flashes' in the sky most often precede Hessdalen
Light phenomena. Sometimes plasma-like orbs overlap with the transient
appearance of apparently structured phenomena. The reason for this connection is not known yet, but it should be investigated in depth."
The next page refers to this:
"3. The constancy of temperature, the self-containment characteristics of
the light balls, and the coexistence of white and red spheres of equal
size.
4. The sudden way in which the phenomenon turns on and off, and the
formation of clusters of light balls, also with characteristics of the expulsion of secondary orbs."